Aqueous carbon nanotube dispersion, paste, cathode and anode

Abstract

A dispersion containing water, a gelling agent, and 0.3 to 2 wt. % of single-walled and/or double-walled carbon nanotubes with a weight ratio of the single-walled and/or double-walled carbon nanotubes to the gelling agent at least 0.05 and not more than 10, wherein the dispersion contains gel particles formed by agglomerates of gelling agent molecules physically bound into a weak gel network by single-walled and/or double-walled carbon nanotubes. Also disclosed a method for producing a dispersion, a method for producing cathode and anode slurries, cathode and anode slurries, and a cathode and an anode are provided. The problems of obtaining an aqueous dispersion of single-walled and/or double-walled carbon nanotubes with both high stability during storage and transportation and low viscosity under various processes of its application, and producing electrode slurries and then lithium-ion battery electrodes, are addressed.

Claims

1. A dispersion, comprising: water; a gelling agent; and single-walled carbon nanotubes, wherein the single-walled carbon nanotubes are between 0.3 to 2 wt. % of the dispersion, wherein a weight ratio of the single-walled carbon nanotubes to the gelling agent is at least 0.05 and not more than 10, and wherein the dispersion is a weak gel that includes the single-walled carbon nanotubes that are physically bound with gel particles formed by agglomerates of molecules of the gelling agent.

2. The dispersion of claim 1, wherein the dispersion is a pseudoplastic power-law fluid with a flow behavior index n not more than 0.37 and a flow consistency index K of at least 3.2 Pa.Math.s.sup.n.

3. The dispersion of claim 1, wherein the dispersion has a loss modulus of at least 27 Pa when an oscillating shear strain at a frequency of 1 Hz and a relative shear strain amplitude of 1% is applied.

4. The dispersion of claim 1, wherein the gelling agent is any of carboxymethylcellulose or its salt, polyvinylpyrrolidone, polyacrylic acid or its salt, or a mixture thereof.

5. The dispersion of claim 1, wherein the single-walled carbon nanotubes contain at least 0.1 wt. % of functional groups on their surfaces.

6. The dispersion of claim 5, wherein the single-walled carbon nanotubes contain at least 0.1 wt. % of chlorine and/or at least 0.1 wt. % of carbonyl and/or hydroxyl, and/or carboxyl groups on their surfaces.

7. The dispersion of claim 1, wherein a ratio of the G/D line intensities in a Raman spectrum of the single-walled carbon nanotubes at a wavelength of 532 nm is at least 10.

8. The dispersion of claim 1, wherein the single-walled carbon nanotubes and/or agglomerates thereof contain Group 8-11 metal impurities.

9. The dispersion of claim 8, wherein a content of Group 8-11 metal impurities in single-walled carbon nanotubes and/or agglomerates thereof is less than 1 wt. %.

10. The dispersion of claim 1, wherein a flow behavior index n and a flow consistency index K of the dispersion meet a condition n<1.25.Math.lg (K/(Pa.Math.s.sup.n))0.628 or n<1.24-0.787.Math.lg (K/(Pa.Math.s.sup.n)).

11. A dispersion, comprising: water; a gelling agent; and single-walled and/or double-walled carbon nanotubes, each of the carbon nanotubes having a diameter of up to 4 nm, wherein the carbon nanotubes are between 0.3 to 2 wt. % of the dispersion, wherein a weight ratio of the carbon nanotubes to the gelling agent is between 0.05 and 10, and wherein the dispersion is a pseudoplastic weak gel.

12. The dispersion of claim 11, wherein the carbon nanotubes are physically bound with gel particles formed by agglomerates of molecules of the gelling agent.

13. The dispersion of claim 11, wherein the agglomerates contain Group 8-11 metal impurities.

14. The dispersion of claim 11, wherein the carbon nanotubes have a Raman G/D ratio of at least 40 at 532 nm.

15. The dispersion of claim 11, wherein the pseudoplastic weak gel is a power law fluid with a flow behavior index n of less than 0.37.

16. The dispersion of claim 11, wherein the pseudoplastic weak gel is a power law fluid with a flow consistency index K of not less than 3.2 Pa.Math.s.sup.n.

17. The dispersion of claim 11, wherein the gelling agent is any of carboxymethylcellulose or its salt, polyvinylpyrrolidone, polyacrylic acid or its salt, or a mixture thereof.

Description

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

(1) The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

(2) In the drawings:

(3) FIG. 1 illustrates transmission electron micrographs of Tuball single-walled carbon nanotubes in dispersions of Examples 1, 5 and 7, as well as Comparative Example 8.

(4) FIG. 2 illustrates dynamic viscosity (Pa.Math.s) of dispersion of Example 1 (circles), Example 2 (squares), Comparative Example 8 (dark triangles) as a function of shear rate (s.sup.1).

(5) FIG. 3 illustrates dynamic viscosity (Pa.Math.s) of cathode slurries of Example 1 (circles) and Comparative Example 8 (dark squares), and anode slurries of Example 1 (diamonds) and Comparative Example 8 (dark triangles) as a function of shear rate (s.sup.1).

(6) FIG. 4 illustrates photos of a cathode slurry layer applied to the current collector of Example 1 (left) and Comparative Example 8 (right).

(7) FIG. 5 illustrates capacity related to initial capacity as a function of the number of charge-discharge cycles (charge rate 1C, discharge rate 1C) of the lithium-ion battery with cathode and anode of Example 1.

(8) FIG. 6 illustrates capacity related to initial capacity as a function of the number of charge-discharge cycles (charge rate 1C, discharge rate 1C) of the lithium-ion battery with cathode and anode of Example 2.

(9) FIG. 7 illustrates capacity related to initial capacity as a function of the number of charge-discharge cycles (charge rate 1C, discharge rate 1C) of the lithium-ion battery with cathode and anode of Example 3.

(10) FIG. 8 illustrates transmission electron micrographs of single-walled and double-walled carbon nanotubes of dispersions of Example 4.

(11) FIG. 9 illustrates capacity related to initial capacity as a function of the number of charge-discharge cycles (charge rate 1C, discharge rate 1C) of the lithium-ion battery with cathode and anode of Example 5.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(12) Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

Example 1

(13) Dispersion Production and Description.

(14) The dispersion contains 0.6 wt. % of the Na-carboxymethylcellulose as gelling agent and 0.4 wt. % of single-walled carbon nanotubes and agglomerates thereof in water. The single-walled carbon nanotubes used for producing the dispersion are Tuball SWCNTs. The SWCNT diameter is in the range of 1.2 to 2.1 nm, with a mean diameter of 1.54 nm (the diameter was determined by TEM of the dry suspension matter, and by the positions of the absorption bands S.sub.1-1 in the optical absorption spectrum of the suspension). Raman spectroscopy at 532 nm shows a strong G line at 1580 cm.sup.1 typical for single-walled carbon nanotubes, and a D line at ca. 1330 cm.sup.1 typical for other allotropic forms of carbon and defects of single-walled carbon nanotubes. The G/D line intensity ratio is 80. The specific surface area determined from nitrogen adsorption isotherms is 1220 m.sup.2/g. See FIG. 1 for the transmission electron micrographs of the SWCNTs used. The SWCNTs for producing the dispersion were further modified with chlorine by the method described in the invention [RU2717516C2; MCD TECH, Mar. 23, 2020; IPC: C01B32/174, B82B3/00, B82B1/00]. The energy dispersion spectroscopy shows that the chlorine content in the Tuball SWCNT is 0.25 wt. %. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) shows that the SWCNTs contain an impurity of 0.46 wt. % of iron, the Group 8 metal. The weight ratio of single-walled carbon nanotubes to the gelling agent in the slurry is 0.667.

(15) The dispersion was produced by mixing the required proportions of water, carboxymethylcellulose Na salt, and SWCNTs and 10-fold dispersing in a NETZSCH Omega 500 high-pressure homogenizer at a pressure of 65 MPa and a dispersion transfer rate of 300 kg/h through the nozzle with a diameter of 700 m. The shear rate in the nozzle is about 6.Math.10.sup.5 s.sup.1. The power consumption was 8 kW, the specific input energy at a stage (D) was about 27 W.Math.h/kg. Between each two dispersion stages, the dispersion was held in a 50 liter tank at rest and agitated slowly by a gate agitator and at a shear rate of about 1 s.sup.1 for 10 minutes.

(16) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 912 Pa, and the loss modulus G=190 Pa, which means that the dispersion is a highly viscous gel.

(17) The dispersion is characterized by the viscosity (Pa.Math.s) as a function of shear rate (s.sup.1) provided in FIG. 2 as circles (curve 1). The viscosity was measured at a constant temperature of 25 C. using a Brookfield DV2-TLV viscometer with an SC4-21 spindle. The viscosity as a function of shear rate is well described by the Ostwald-de Waele power law in a range from 0.093 s.sup.1 to 93 s.sup.1. The flow behavior index n is 0.13, and the flow consistency index is 9.0 Pa.Math.s.sup.0.13. The dispersion viscosity in the area of low shear rates of less than 1/6.3 s.sup.1 is more than 43 Pa.Math.s, and it is less than 0.72 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1.

(18) Using the dispersion to produce the cathode slurry and the cathode.

(19) The dispersion was used to produce the cathode slurry containing 58.65 wt. % of active material LiFePO.sub.4, 40 wt. % of water as solvent, 0.72 wt. % of styrene butadiene rubber binder, 0.6 wt. % of Na-carboxymethylcellulose gelling agent, and 0.03 wt. % of single-walled carbon nanotubes. The cathode slurry was produced by the sequence of stages: adding 54 g of a solution containing 0.925 g of Na-carboxymethylcellulose and 53.075 g of water to 12.5 g of this dispersion, mixing on an overhead stirrer for 30 minutes (an additional stage of adding binder and solvent implemented before the stage (C1) and before the stage (C2)); mixing the resultant mixture with 97.75 g of the active component LiFePO.sub.4 (stage C1); adding 2.4 g of aqueous styrene butadiene rubber latex with a dry matter content of 50% (an additional binder adding stage implemented before the stage (C2)); agitating for 16 hours to produce a homogeneous slurry (stage C2).

(20) With both the single-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant cathode slurry has the sharply pronounced dependence of viscosity on shear rate represented by circles (curve 1C) in FIG. 3. The flow behavior index is 0.26. The viscosity measured at a shear rate of 93 s.sup.1 is 0.76 Pa.Math.s, and the dependence extrapolation to a shear rate of 100 s.sup.1 gives a viscosity estimate of about 0.70 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of less than 1 s.sup.1, the viscosity is more than 21 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(21) The storage stability of the slurry was determined by the changing distribution of the solid particles content along the height of the slurry layer after the slurry storage in a 50 ml cylindrical test tube with a diameter of 30 mm. For this purpose, the slurry was put in the test tube, closed with a lid, and kept for 7 days under standard conditions (atmospheric pressure, 25 C.). After that, the upper third, the middle third, and the lower third of the test tube were collected with a pipette, and the weight fractions of water and solid non-volatile components in the samples were determined by drying. For the cathode slurry of this Example, the water content in the initial slurry was 40.0 wt. %, after one-week storage, the solvent content was 41.0 wt. % in the upper third, 39.8 wt. % in the middle part, and 39.2 wt. % in the lower part. The relative difference from the initial solvent content does not exceed 2.5%, which is significantly less than for the slurry described below in Comparative Example 8, and it is indicative of high stability of the resultant slurry. The slurry can be used to produce the cathode after 7-day storage.

(22) The lithium-ion battery cathode was produced by applying the resultant slurry to an aluminum foil of the current collector, drying the applied slurry until the cathode is formed, and compacting the cathode on a calender with a force of 5 tons to the required density of 2.5 mg/cm.sup.2. The photo of the cathode slurry layer applied to the current collector is shown in FIG. 4 (left photo). The cathode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 5% v/v of vinyl carbonate. The initial specific capacity of the cathode at a discharge current of 0.015 A/g of the cathode material is 158 mA.Math.h/g of the cathode material.

(23) Using the dispersion to produce the anode slurry and the anode.

(24) The dispersion was used to produce the anode slurry containing 31.3 wt. % of graphite active material, 14.2 wt. % of silicon active material, 53.6 wt. % of water solvent, 0.35 wt. % of Na-carboxymethylcellulose gelling agent, 0.84 wt. % of styrene butadiene latex binder, and 0.23 wt. % of single-walled carbon nanotubes. The anode slurry was produced by the sequence of stages: mixing 187.5 g of the dispersion, 1500 g of water, 1000 g of graphite powder, and 454.2 g of silicon powder, agitating for 10 hours (stage A1 where additional water is introduced); adding 54 g of 50 wt. % of aqueous styrene butadiene latex suspension (an additional binder adding stage implemented before the stage (A2)); agitating for 4 hours to produce a homogeneous slurry (stage A2).

(25) With both the single-walled carbon nanotubes and the gelling agent present, the resultant anode slurry also has a sharply pronounced dependence of viscosity on shear rate represented by diamonds (curve 1A) in FIG. 3. The dependence follows the Ostwald-de Waele power law with a flow behavior index 0.17 and a flow consistency index 11.5 Pa.Math.s.sup.0.17. With a shear rate of 100 s.sup.1, the slurry viscosity is less than 0.26 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of less than 1 s.sup.1, the viscosity is more than 11.6 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(26) The storage stability of the anode slurry was tested by the above method for the cathode slurry. Within a week, the water content in the upper third of the slurry increased from 53.6 wt. % to 54.2 wt. %, i.e., less than 2% relative of the initial value. This is indicative of a high slurry stability.

(27) For the anode production, the resultant anode slurry was applied to a copper foil using a doctor blade, dried at a temperature of 40 C. for 1 hour and compacted on a calender with a force of 5 tons to an anode material density of 1.4 g/cm.sup.3. The load of the active material on the anode is 8.5 mg/cm.sup.2. The anode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 1% v/v of vinyl carbonate. The initial specific capacity of the anode at a charge current of 0.03 A/g of the anode material is 342 mA.Math.h/g of the anode material.

(28) The lithium-ion battery was assembled from the resultant cathode and anode. A 16 m thick polypropylene separator was used. A 0.8 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents in a volume ratio of 1:1:1 with additional 1% v/v of vinyl carbonate was used as an electrolyte. The initial battery capacity at a discharge rate of 0.1 C was 324 mA.Math.h. The capacity (referred to the initial capacity) as a function of the number of charge-discharge cycles (charge current 324 mA, discharge current 324 mA) is shown in FIG. 5. The battery capacity is more than 90% of the initial capacity after 3000 cycles.

Example 2

(29) The dispersion contains 0.6 wt. % of the polyvinylpyrrolidone (PVP) gelling agent and 0.3 wt. % of single-walled carbon nanotubes and agglomerates thereof, the rest is water. The dispersion was produced using Tuball SWCNTs subjected to multistage chemical purification and boiling in nitric acid for 4 hours. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) shows that the content of Fe in the SWCNTs is 60 ppm or 0.06 wt. %. The potentiometric titration shows that the SWCNT surface after such treatment contains about 0.62 wt. % of carboxyl groups. The SWCNT diameter is distributed in a range of 1.2 to 2.1 nm with a mean diameter of 1.60 nm, the G/D line intensity ratio is 24, and the specific surface area determined from nitrogen adsorption isotherms is 1280 m.sup.2/g. The weight ratio of single-walled carbon nanotubes to the gelling agent in the slurry is 0.667.

(30) The dispersion was produced by mixing the required proportions of water, polyvinylpyrrolidone and SWCNT, 8-fold repeating the alternating stages of dispersing in a Chaoli GJB500 high-pressure homogenizer and holding at rest in a 65 liter tank while agitating slowly by a gate agitator at a shear rate of about 1 s.sup.1 for 12 minutes. The dispersion occurred at a pressure of 60 MPa, a dispersion transfer flow rate of 300 l/h, and a shear rate in the valve nozzle of about 6.Math.10.sup.5 s.sup.1. The measured power consumption was 16 kW, the specific input energy at the stage (D) was about 53 W.Math.h/kg.

(31) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 2460 Pa, and the loss modulus G=390 Pa, which means that the dispersion is a highly viscous gel.

(32) The dispersion is characterized by the viscosity (Pa.Math.s) as a function of shear rate (s.sup.1) provided in FIG. 2 as square markers. The flow behavior index n is 0.156, and the flow consistency index is 21.6 Pa.Math.s.sup.0.156. The dispersion viscosity in the area of low shear rates of less than 1/6.3 s.sup.1 is more than 100 Pa.Math.s, and it is less than 1.9 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1.

(33) The dispersion was used to produce the cathode slurry containing 61 wt. % of active material LiNi.sub.0.33Co.sub.0.33Mn.sub.0.33O.sub.2 (NCM111), 37.7 wt. % of water solvent, 0.62 wt. % of styrene butadiene rubber binder, 0.62 wt. % of Na-carboxymethylcellulose binder, 0.047 wt. % of PVP gelling agent, and 0.023 wt. % of single-walled carbon nanotubes. The cathode slurry was produced by the sequence of stages: adding 240 g of a solution containing 5 g of Na-carboxymethylcellulose and 235 g of water to 62.5 g of this dispersion, mixing on an overhead stirrer for 30 minutes (an additional binder and solvent adding stage implemented before the stage (C1) and before the stage (C2)); mixing the resultant mixture with 488 g of the active component NCM111 (stage C1); adding 10 g of aqueous styrene butadiene rubber latex with a dry matter content of 50% (an additional binder adding stage implemented before the stage (C2)); agitating for 16 hours to produce a homogeneous slurry (stage C2).

(34) With both the single-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant cathode slurry has a sharply pronounced dependence of viscosity on shear rate, which is well described by the power law with a flow behavior index 0.24 and a flow consistency index 18.8 Pa.Math.s. With a shear rate of 100 s.sup.1, the dynamic viscosity is about 0.55 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of not more than 1 s.sup.1, the viscosity is at least 18.8 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(35) The slurry storage stability was determined by the method described in Example 1. For the cathode slurry of this Example, the water content in the initial slurry was 37.7 wt. %, after one-week storage, the water content was 38.2 wt. % in the upper third, 37.9 wt. % in the middle part, and 37.0 wt. % in the lower part. The relative difference from the initial solvent content does not exceed 2%, which is within the measurement error. The slurry can be used to produce the cathode after 7-day storage.

(36) The lithium-ion battery cathode was produced by applying the resultant slurry to an aluminum foil of the current collector, drying the applied slurry until the cathode is formed, and compacting the cathode on a calender with a force of 5 tons to the required density of 3.6 mg/cm.sup.2. The cathode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 1% v/v of vinyl carbonate. The initial specific capacity of the cathode at a discharge current of 0.015 A/g of the cathode material is 155 mA.Math.h/g of the cathode material.

(37) The dispersion was used to produce the anode slurry containing 26.6 wt. % of graphite active material, 16.2 wt. % of silicon active material, 55.5 wt. % of water solvent, 0.33 wt. % of polyvinylpyrrolidone gelling agent, 0.49% of Na-carboxymethylcellulose binder, 0.66 wt. % of styrene butadiene latex binder, and 0.17 wt. % of single-walled carbon nanotubes. The anode slurry was produced by the sequence of stages: adding 367 g of silicon powder and 600 g of graphite powder to 1250 g of the dispersion, agitating for 1 hour (stage (A1)); adding 11 g of Na-carboxymethylcellulose powder, agitating for 1 hour; (an additional binder adding stage implemented before the stage (A2)); adding 30 g of 50 wt. % of aqueous butadiene styrene latex suspension (an additional binder adding stage implemented before the stage (A2)); agitating for 16 hours to produce a homogeneous slurry (stage A2).

(38) For the anode production, the resultant anode slurry was applied to a copper foil using a doctor blade, dried at a temperature of 80 C. for 15 minutes and compacted on a calender with a force of 5 tons to an anode material density of 1.0 g/cm.sup.3. The anode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 10% v/v of fluoroethylene carbonate. The initial specific capacity of the anode at a charge current of 0.3 A/g of the anode material is 1360 mA.Math.h/g of the anode material.

(39) With both the single-walled carbon nanotubes and the gelling agent present, the resultant anode slurry has a sharply pronounced dependence of viscosity on shear rate, which follows the Ostwald-de Waele power law with a flow behavior index 0.19 and a flow consistency index 12.3 Pa.Math.s.sup.0.19. With a shear rate of 100 s.sup.1, the slurry viscosity is less than 0.30 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of less than 1 s.sup.1, the viscosity is more than 12.3 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(40) The storage stability of the anode slurry was tested by the above method for the cathode slurry. Within a week, the water content in the upper third of the slurry increased from 55.6 wt. % to 57.0 wt. %, i.e., less than 3 rel. % of the initial value. This is indicative of a high slurry stability.

(41) The lithium-ion battery was assembled from the resultant cathode and anode. A 16 m thick polypropylene separator was used. A 1.5 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents in a volume ratio of 1:1:1 with additional 20% v/v of vinyl carbonate was used as an electrolyte. The initial battery capacity at a discharge rate of 0.1 C was 525 mA.Math.h. The capacity (referred to the initial capacity) as a function of the number of charge-discharge cycles (charge current 525 mA, discharge current 525 mA) is shown in FIG. 6. The battery capacity is more than 96% of the initial capacity after 1000 cycles.

Example 3

(42) The dispersion contains 2 wt. % of the polyacrylic acid Na salt gelling agent and 0.3 wt. % of single-walled carbon nanotubes and agglomerates thereof, and water to balance. The single-walled carbon nanotubes used for producing the dispersion are Tuball SWCNTs. The SWCNT diameter is distributed in a range of 1.2 to 2.1 nm with a mean diameter of 1.62 nm, the G/D line intensity ratio is 46, and the specific surface area determined from nitrogen adsorption isotherms is 580 m.sup.2/g. The thermogravimetry data in the 5% oxygen flow in Ar show that the ash residue after the material oxidation at 950 C. is about 20 wt. %. X-ray diffraction shows that the ash residue predominantly contains iron oxide Fe.sub.2O.sub.3, and the SWCNTs contain a nanodispersed metallic iron phase. The energy dispersive X-ray spectroscopy shows that the Fe content in the SWCNTs is 14.2 wt. %, which is consistent with the data on ash residue weight.

(43) The dispersion was produced by mixing the required proportions of water, Na salt of polyacrylic acid, and SWCNTs and 15-fold repeating the alternating stages: dispersing in a rotary pulsation apparatus (RPA) with a power consumption of 32 kW, a rotor diameter of 190 mm, a gap between the rotor and the stator of 700 m, and a rotor speed of 2940 rpm, ultrasonic treatment in a 100 liter tank at a frequency of 40 kHz and the acoustic input power of the sonotrode 1800 W, and at rest in a 220 liter tank while agitating slowly by an anchor agitator at 30 rpm and a shear rate of about 2 s.sup.1. The rate of dispersion circulation between the RPA, the probe sonicator, and the tank is 1000 kg/h; about 32 W.Math.h/kg of energy is applied to the dispersion in the RPA at the dispersion stage (D); about 1.8 W.Math.h/kg is applied to the dispersion at the ultrasonic treatment stage (D); the mean tank residence time of the dispersion at a shear rate of about 2 s.sup.1 is about 13 minutes at the stage (R).

(44) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 1150 Pa, and the loss modulus G=410 Pa, which means that the dispersion is a highly viscous gel.

(45) The dispersion is characterized by a sharp decrease in viscosity with higher shear rate, which is well described by the power law. The flow behavior index n is 0.23, and the flow consistency index is 19.0 Pa.Math.s.sup.0.23. The dispersion viscosity is more than 78 Pa.Math.s in the area of low shear rates of less than 1/6.3 s.sup.1, and it is less than 0.53 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1, which, on the one hand, provides high dispersion storage stability and, on the other hand, its processability in various implementations, including the production of electrode slurries for the production of lithium-ion battery electrodes.

(46) The dispersion was used to produce the cathode slurry containing 29.9 wt. % of active material LiCo.sub.2O.sub.4 (LCO), 68.6 wt. % of water solvent, 1.25 wt. % of Na-PAA gelling agent, and 0.19 wt. % of single-walled carbon nanotubes. The cathode slurry was produced by the sequence of stages: adding 235 g of water to 2000 g of the dispersion, mixing on an overhead stirrer for 30 minutes (an additional solvent adding stage implemented before the stage (C1) and before the stage (C2)); mixing the resultant mixture with 954 g of the active component LCO (stage C1); agitating for 16 hours to produce a homogeneous slurry (stage C2).

(47) With both the single-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant cathode slurry has a sharply pronounced dependence of viscosity on shear rate, which is well described by the power law with a flow behavior index 0.20 and a flow consistency index 12.1 Pa.Math.s.sup.0.2. With a shear rate of 100 s.sup.1, the dynamic viscosity is about 0.30 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of not more than 1 s.sup.1, the viscosity is at least 12.1 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(48) The slurry storage stability was determined by the method described in Example 1. For the cathode slurry of this Example, the water content in the initial slurry was 68.6 wt. %, after one-week storage, the water content was 70.2 wt. % in the upper third, 69.0 wt. % in the middle part, and 66.4 wt. % in the lower part. The difference from the initial content of the solvent does not exceed 3.5 rel. %. The slurry can be used to produce the cathode after 7-day storage.

(49) The lithium-ion battery cathode was produced by applying the resultant slurry to an aluminum foil of the current collector, drying the applied slurry until the cathode is formed, and compacting the cathode on a calender with a force of 10 tons to the required density of 4.2 mg/cm.sup.2. The cathode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1.2 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 1% v/v of vinyl carbonate. The initial specific capacity of the cathode at a discharge current of 0.0125 A/g of the cathode material is 123 mA.Math.h/g of the cathode material.

(50) The dispersion was used to produce the anode slurry containing 18.5 wt. % of silicon oxide (SiO.sub.x) active material, 79.7 wt. % of water solvent, 1.63 wt. % of PAA gelling agent, and 0.24 wt. % of single-walled carbon nanotubes. The anode slurry was produced by the sequence of stages: adding 181 g of SiO.sub.x powder to 800 g of this dispersion (stage A1); agitating for 16 hours to produce a homogeneous slurry (stage A2).

(51) With both the single-walled carbon nanotubes and the gelling agent present, the resultant anode slurry has a sharply pronounced dependence of viscosity on shear rate, which follows the Ostwald-de Waele power law with a flow behavior index 0.17 and a flow consistency index 10.5 Pa.Math.s.sup.0.17. With a shear rate of 100 s.sup.1, the slurry viscosity is less than 0.23 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of less than 1 s.sup.1, the viscosity is more than 10.5 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(52) The storage stability of the anode slurry was tested by the above method for the cathode slurry. Within a week, the water content in the upper third of the slurry increased from 80 wt. % to 81 wt. %, i.e., less than 2 rel. % of the initial value. This is indicative of a high slurry stability.

(53) For the anode production, the resultant anode slurry was applied to a copper foil using a doctor blade, dried at a temperature of 70 C. for 15 minutes and compacted on a calender with a force of 5 tons to an anode material density of 1.3 g/cm.sup.3. The anode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 10% v/v of fluoroethylene carbonate. The initial specific capacity of the anode at a charge current of 0.1 A/g of the anode material is 1652 mA.Math.h/g of the anode material.

(54) The lithium-ion battery was assembled from the resultant cathode and anode. A 16 m thick polypropylene separator was used. A 1.5 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents in a volume ratio of 1:1:1 with additional 20% v/v of fluoroethylene carbonate was used as an electrolyte. The initial battery capacity at a discharge rate of 0.1 C was 1200 mA.Math.h. The capacity (referred to the initial capacity) as a function of the number of charge-discharge cycles (charge current 1200 mA, discharge current 1200 mA) is shown in FIG. 7. The battery capacity is more than 85% of the initial capacity after 215 cycles.

Example 4

(55) The dispersion is similar to the one described in Example 1, but contains a mixture of single-walled and double-walled carbon nanotubes with diameters from 1.2 to 2.8 nm and a mean diameter of 1.8 nm (the diameter was determined by TEM of the dry suspension matter and from the positions of the radial breathing mode (RBM) lines in the Raman spectra). The intensity ratio of the G/D lines in the Raman spectrum of light with a wavelength of 532 nm is 34. The availability of double-walled carbon nanotubes bundled together with single-walled carbon nanotubes is confirmed by the electron micrographs provided in FIG. 8. The concentration of carbon nanotubes in the dispersion is 0.4 wt. %. The dispersion also contains 0.6 wt. % of the carboxymethylcellulose Na salt gelling agent. The weight ratio of single-walled carbon nanotubes to the gelling agent in the slurry is 0.667.

(56) The dispersion was produced by mixing the required proportions of water, Na-carboxymethylcellulose, and SWCNTs and DWCNTs, and 32-fold dispersing in a NETZSCH Omega 500 high-pressure homogenizer at a pressure of 65 MPa and a dispersion transfer rate of 300 kg/h through the nozzle with a diameter of 700 m. The shear rate in the nozzle is about 6.Math.10.sup.5 s.sup.1. The power consumption was 8 kW, the specific input energy at the stage (D) was about 27 W.Math.h/kg. Between each two dispersion stages, the dispersion was held in a 50 liter tank at rest and agitated slowly by a gate agitator and at a shear rate of about 1 s.sup.1 for 10 minutes.

(57) The dispersion is characterized by lower viscosity with increasing shear rate. The viscosity was measured at a constant temperature of 25 C. using a Brookfield DV2-TLV viscometer with an SC4-21 spindle. The viscosity as a function of shear rate is well described by the Ostwald-de Waele power law in a range from 0.093 s.sup.1 to 100 s.sup.1. The flow behavior index n is 0.19, and the flow consistency index is 4.9 Pa.Math.s.sup.0.19. The dispersion viscosity in the area of low shear rates of less than 1/6.3 s.sup.1 is more than 22 Pa.Math.s, and it is less than 0.46 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1.

(58) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 176 Pa, and the loss modulus G=28 Pa, which means that the dispersion is a highly viscous gel.

(59) The dispersion was used to produce the cathode slurry containing 58.65 wt. % of active material LiFePO.sub.4, 40 wt. % of water solvent, 0.72 wt. % of styrene butadiene rubber binder, 0.6 wt. % of Na-carboxymethylcellulose gelling agent, and 0.03 wt. % of single-walled and double-walled carbon nanotubes. The production sequence was similar to Example 1.

(60) With both the single-walled and double-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant cathode slurry has a sharply pronounced dependence of viscosity on shear rate, which is well described by the power law. The flow behavior index is 0.29, and the flow consistency index is 18 Pa.Math.s.sup.0.29. The viscosity measured at a shear rate of 93 s.sup.1 is 0.72 Pa.Math.s, and the dependence extrapolation to a shear rate of 100 s.sup.1 gives a viscosity estimate of about 0.68 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of not more than 1 s.sup.1, the viscosity is at least 18 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(61) The slurry storage stability was determined similarly to Example 1. The water content in the initial slurry was 40.0 wt. %, after one-week storage, the solvent content was 41.4 wt. % in the upper third, 39.7 wt. % in the middle part, and 38.8 wt. % in the lower part. The difference from the initial solvent content does not exceed 3 rel. %, which is significantly less than for the slurry described below in Comparative Example 8, and it is indicative of high stability of the resultant slurry. The slurry can be used to produce the cathode after 7-day storage.

(62) The lithium-ion battery cathode was produced similarly to Example 1. The initial specific capacity of the cathode at a discharge current of 0.015 A/g of the cathode material is 152 mA.Math.h/g of the cathode material.

(63) The dispersion was used to produce the anode slurry containing 31.3 wt. % of graphite active material, 14.2 wt. % of silicon active material, 53.6 wt. % of water solvent, 0.35 wt. % of Na-carboxymethylcellulose gelling agent, 0.84 wt. % of styrene butadiene latex binder, and 0.23 wt. % of single-walled and double-walled carbon nanotubes. The anode slurry production procedure was similar to Example 1.

(64) With both the single-walled carbon nanotubes and the gelling agent in the dispersion, the resultant anode slurry has a sharply pronounced dependence of viscosity on shear rate, which is described by the power law. The flow behavior index is 0.2, and the flow consistency index is 11.0 Pa.Math.s.sup.0.2. With a shear rate of 100 s.sup.1, the slurry viscosity is less than 0.28 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of less than 1 s.sup.1, the viscosity is more than 11.0 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(65) The storage stability of the anode slurry was tested by the above method in Example 1. Within a week, the water content in the upper third of the slurry increased from 53.6 wt. % to 54.7 wt. %, i.e., less than 2 rel. % of the initial value. This is indicative of a high slurry stability.

(66) The anode was produced similarly to Example 1. The initial specific capacity of the anode at a charge current of 0.03 A/g of the anode material is 334 mA.Math.h/g of the anode material.

(67) The lithium-ion battery was assembled from the resultant cathode and anode. A 16 m thick polypropylene separator was used. A 0.8 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents in a volume ratio of 1:1:1 with additional 1% v/v of vinyl carbonate was used as an electrolyte. The initial battery capacity at a discharge rate of 0.03 C was 314 mA.Math.h. The battery capacity is more than 92% of the initial capacity after 400 charge-discharge cycles (charge current 314 mA, discharge current 314 mA).

Example 5

(68) The dispersion contains 0.2 wt. % of the carboxymethylcellulose Li salt gelling agent and 2 wt. % of single-walled carbon nanotubes and agglomerates thereof in water. The dispersion was produced using Tuball SWCNTs modified with chlorine, as described in Example 1. The weight ratio of single-walled carbon nanotubes to the gelling agent in the slurry is 10.

(69) The dispersion was produced by mixing the required proportions of water, polyvinylpyrrolidone and SWCNT, and 32-fold circulating the dispersion at a dispersion transfer rate of 300 kg/h between the Chaoli GJB500 high-pressure disperser (stage (D)) and the 50 liter tank where the dispersion was at rest (stage (R)) while being agitated slowly by a gate agitator at a shear rate of about 2 s.sup.1. The estimated shear rate in the disperser is over 600000 s.sup.1, the measured power consumption was 19 kW. The specific input energy in the dispersion cycle is about 63 W.Math.h/kg. The mean residence time in the tank at the stage (R) was about 10 minutes.

(70) The viscosity was measured at a constant temperature of 25 C. using a Brookfield DV2-TLV viscometer with an SC4-21 spindle. The viscosity as a function of shear rate is well described by the Ostwald-de Waele power law in a range from 0.093 s.sup.1 to 100 s.sup.1. The flow behavior index n is 0.33, and the flow consistency index is 13.5 Pa.Math.s.sup.0.33. The dispersion viscosity in the area of low shear rates of less than 1/6.3 s.sup.1 is more than 45 Pa.Math.s, and it is less than 1.9 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1.

(71) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 980 Pa, and the loss modulus G=460 Pa, which means that the dispersion is a highly viscous gel.

(72) The dispersion was used to produce the cathode slurry containing 55.1 wt. % of active material LiFePO.sub.4, 42.3 wt. % of water solvent, 0.57 wt. % of styrene butadiene rubber binder, 1.22 wt. % of carboxymethylcellulose Li salt gelling agent and binder, and 0.85 wt. % of single-walled carbon nanotubes. The cathode slurry was produced by the sequence of stages: adding 20 g of Li-carboxymethylcellulose powder and 968.5 g of active component LiFePO.sub.4 (stage (C1) where an additional binder is introduced) to 750 g of this dispersion; adding 20 g of aqueous styrene butadiene rubber latex suspension with a dry matter content of 50 wt. % (an additional binder adding stage implemented before the stage (C2)); agitating for 16 hours to produce a homogeneous slurry (stage C2).

(73) With both the single-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant cathode slurry has a sharply pronounced dependence of viscosity on shear rate, which is well described by the power law with a flow behavior index 0.18 and a flow consistency index 19.9 Pa.Math.s.sup.0.18. With a shear rate of 100 s.sup.1, the dynamic viscosity is about 0.46 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of not more than 1 s.sup.1, the viscosity is at least 19.9 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(74) The slurry storage stability was determined by the method described in Example 1. For the cathode slurry of this Example, the water content in the initial slurry was 42.3 wt. %, after one-week storage, the water content was 43.0 wt. % in the upper third, 42.5 wt. % in the middle part, and 41.5 wt. % in the lower part. The difference from the initial content of the solvent does not exceed 2 rel. %. The slurry can be used to produce the cathode after 7-day storage.

(75) The lithium-ion battery cathode was produced using the resultant cathode slurry similarly to Example 1. The initial specific capacity of the cathode at a discharge current of 0.15 A/g of the cathode material is 147 mA.Math.h/g of the cathode material.

(76) Using the dispersion to produce the anode slurry and the anode.

(77) The dispersion was used to produce the anode slurry containing 18 wt. % of graphite active material, 32.9 wt. % of silicon oxide active material, 44.6 wt. % of water solvent, 3.1 wt. % of carboxymethylcellulose Li salt gelling agent and binder, 0.6 wt. % of styrene butadiene rubber binder, and 0.9 wt. % of single-walled carbon nanotubes. The anode slurry was produced by the sequence of stages: mixing 37.5 g of the dispersion, 2.5 g of carboxymethylcellulose Li salt powder, 15 g of graphite powder, and 27.4 g of silicon powder, agitating for 1 hour (stage (C1) where an additional binder is introduced); adding 1 g of aqueous styrene butadiene rubber latex suspension with a dry matter content of 50 wt. % (an additional stage of adding a binder and water, implemented before the stage (A2)); agitating for 10 hours to produce a homogeneous slurry (stage A2).

(78) With both the single-walled carbon nanotubes and the gelling agent present, the resultant anode slurry also has a sharply pronounced dependence of viscosity on shear rate, which is described by the power law. The flow behavior index is 0.17, and the flow consistency index is 20.4 Pa.Math.s.sup.0.17. With a shear rate of 100 s.sup.1, the slurry viscosity is less than 0.45 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of less than 1 s.sup.1, the viscosity is more than 20.4 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(79) The storage stability of the anode slurry was tested by the above method in Example 1. Within a week, the water content in the upper third of the slurry increased from 44.6 wt. % to 45.2 wt. %, i.e., less than 2 rel. % of the initial value. This is indicative of a high slurry stability.

(80) For the anode production, the resultant anode slurry was applied to a copper foil using a doctor blade, dried at a temperature of 100 C. for 1 hour and compacted on a calender with a force of 5 tons to an anode material density of 1.6 g/cm.sup.3. The load of the active material on the anode is 5.5 mg/cm.sup.2. The anode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 10% v/v of fluoroethylene carbonate. The initial specific capacity of the anode at a charge current of 0.1 A/g of the anode material is 900 mA.Math.h/g of the anode material.

(81) The lithium-ion battery was assembled from the resultant cathode and anode. A 16 m thick polypropylene separator was used. A 1.5 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents in a volume ratio of 1:1:1 with additional 20% v/v of fluoroethylene carbonate was used as an electrolyte. The initial battery capacity at a discharge rate of 0.1 C was 1200 mA.Math.h. The capacity (referred to the initial capacity) as a function of the number of charge-discharge cycles (charge current 1200 mA, discharge current 1200 mA) is shown in FIG. 9. The battery capacity is more than 96% of the initial capacity after 800 cycles.

Example 6

(82) The dispersion contains 2 wt. % of the carboxymethylcellulose Na salt gelling agent and 0.3 wt. % of single-walled carbon nanotubes and agglomerates thereof in water. The single-walled carbon nanotubes used for producing the dispersion are Tuball-99 SWCNTs. The SWCNT diameter is in the range of 1.2 to 2.1 nm, with a mean diameter of 1.58 nm (the diameter was determined by TEM of the dry suspension matter, and by the positions of the absorption bands S.sub.1-1 in the optical absorption spectrum of the suspension). Raman spectroscopy at 532 nm shows a strong G line at 1580 cm.sup.1 typical for single-walled carbon nanotubes, and a D line at ca. 1330 cm.sup.1 typical for other allotropic forms of carbon and defects of single-walled carbon nanotubes. The G/D line intensity ratio is 56. The specific surface area determined from nitrogen adsorption isotherms is 1160 m.sup.2/g. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) shows that the SWCNTs contain an impurity of 0.4 wt. % of iron, metal of the Group 8 of the Periodic Table of Elements. The weight ratio of single-walled carbon nanotubes to the HNBR in the slurry is 0.15.

(83) The dispersion was produced by mixing the required proportions of water, carboxymethylcellulose Na salt, and SWCNTs and 6-fold dispersing in a NETZSCH Omega 500 high-pressure homogenizer at a pressure of 65 MPa and a dispersion transfer rate of 300 kg/h through the nozzle with a diameter of 700 m. The shear rate in the nozzle is about 6.Math.10.sup.5 s.sup.1. The power consumption was 9 kW, the specific input energy at the stage (D) was about 30 W.Math.h/kg. Between each two dispersion stages, the dispersion was held in a 100 liter tank at rest and agitated slowly by a gate agitator and at a shear rate of about 3 s.sup.1 for 20 minutes.

(84) The viscosity was measured at a constant temperature of 25 C. using a Brookfield DV2-TLV viscometer with an SC4-21 spindle. The viscosity as a function of shear rate is well described by the Ostwald-de Waele power law in a range from 0.093 s.sup.1 to 100 s.sup.1. The flow behavior index n is 0.13, and the flow consistency index is 20.5 Pa.Math.s.sup.0.13. The dispersion viscosity in the area of low shear rates of less than 1/6.3 s.sup.1 is more than 100 Pa.Math.s, and it is less than 1.6 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1.

(85) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 2800 Pa, and the loss modulus G=320 Pa, which means that the dispersion is a highly viscous gel.

(86) The dispersion was used to produce the cathode slurry containing 66.1 wt. % of active material LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 (NCM622), 30.3 wt. % of N-methylpyrrolidone (NMP) solvent, 2.2 wt. % of water, 1.32 wt. % of PVDF binder, 0.046 wt. % of carboxymethylcellulose Na salt gelling agent, and 0.0069 wt. % of single-walled carbon nanotubes. The cathode slurry was produced by the sequence of stages: adding 110 g of N-methylpyrrolidone and 4.8 g of polyvinylidene fluoride (PVDF) powder to 8.3 g of the dispersion, mixing on an overhead stirrer for 30 minutes (an additional stage to introduce additional solvent (NMP) and binder before the stage (C2)); mixing the resultant mixture with 240 g of the active component NCM622 (stage (C1)); agitating for 16 hours to produce a homogeneous slurry (stage (C2)).

(87) With both the single-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant cathode slurry has a sharply pronounced dependence of viscosity on shear rate, which is well described by the power law with a flow behavior index 0.28 and a flow consistency index 22 Pa.Math.s.sup.0.28. With a shear rate of 100 s.sup.1, the dynamic viscosity is about 0.80 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of not more than 1 s.sup.1, the viscosity is at least 22 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(88) The slurry storage stability was determined by the method described in Example 1. The solvent (water and NMP) content in the initial slurry was 32.5 wt. %, after one-week storage, the water content was 32.8 wt. % in the upper third, 32.7 wt. % in the middle part, and 32.1 wt. % in the lower part. The difference from the initial content of the solvents does not exceed 2 rel. %. The slurry can be used to produce the cathode after 7-day storage.

(89) The lithium-ion battery cathode was produced by applying the resultant slurry to an aluminum foil of the current collector, drying the applied slurry until the cathode is formed, and compacting the cathode on a calender with a force of 5 tons to the required density of 3.7 mg/cm.sup.2. The cathode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 5% v/v of vinyl carbonate. The initial specific capacity of the cathode at a discharge current of 0.017 A/g of the cathode material is 173 mA.Math.h/g of the cathode material.

(90) The dispersion was used to produce the anode slurry containing 39 wt. % of graphite active material, 4.5 wt. % of silicon oxide SiO.sub.x active material, 55.1 wt. % of water solvent, 1.35 wt. % of carboxymethylcellulose Na salt (Na-CMC) gelling agent and binder, and 0.027 wt. % of single-walled carbon nanotubes. The anode slurry was produced by the sequence of stages: mixing 11.7 of the dispersion, 50 g of water, 1.27 g of Na-CMC powder, 43.5 g of graphite powder and 5 g of SiO.sub.x silicon oxide powder (stage (A1) where additional water solvent and Na-CMC binder were introduced), and agitating for 12 hours to produce a homogeneous slurry (stage (A2)).

(91) With both the single-walled carbon nanotubes and the gelling agent present, the resultant anode slurry has a sharply pronounced dependence of viscosity on shear rate, which is described by the power law. The flow behavior index is 0.25, and the flow consistency index is 11.6 Pa.Math.s.sup.0.25. With a shear rate of 100 s.sup.1, the slurry viscosity is less than 0.37 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of less than 1 s.sup.1, the viscosity is more than 11.6 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(92) The storage stability of the anode slurry was tested by the above method in Example 1. Within a week, the water content in the upper third of the slurry increased from 55 wt. % to 55.6 wt. %, i.e., less than 2 rel. % of the initial value. This is indicative of a high slurry stability.

(93) For the anode production, the resultant anode slurry was applied to a copper foil using a doctor blade, dried at a temperature of 100 C. for 1 hour and compacted on a calender with a force of 5 tons to an anode material density of 1.5 g/cm.sup.3. The anode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of propylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 10% v/v of fluoroethylene carbonate. The initial specific capacity of the anode at a charge current of 0.1 A/g of the anode material is 420 mA.Math.h/g of the anode material.

(94) The lithium-ion battery was assembled from the resultant cathode and anode. A 16 m thick polypropylene separator was used. A 1.5 M solution of LiPF.sub.6 in the mixture of ethylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents in a volume ratio of 1:1:1 with additional 20% v/v of fluoroethylene carbonate was used as an electrolyte. The initial battery capacity at a discharge rate of 0.1 C was 2400 mA.Math.h. The battery capacity is more than 85% of the initial capacity after 500 charge-discharge cycles (charge current 800 mA, discharge current 800 mA).

Example 7

(95) The dispersion contains 0.8 wt. % of the carboxymethylcellulose Na salt gelling agent and 0.8 wt. % of single-walled carbon nanotubes and agglomerates thereof in water. The dispersion was produced using Tuball SWCNTs modified with chlorine, as described in Example 1. The weight ratio of single-walled carbon nanotubes to the gelling agent in the slurry is 1.

(96) The dispersion was produced by mixing the required proportions of water, Na salt of polyacrylic acid, and SWCNTs and 15-fold repeating the alternating stages: dispersing in a rotary pulsation apparatus (RPA) with a power consumption of 32 kW, a rotor diameter of 190 mm, a gap between the rotor and the stator of 700 m, and a rotor speed of 2940 rpm, ultrasonic treatment in a 100 liter tank at a frequency of 40 kHz and the acoustic input power of the sonotrode 1600 W, and at rest in a 65 liter tank while agitating slowly by an anchor agitator at 30 rpm and a shear rate of about 2 s.sup.1. The rate of dispersion circulation between the RPA, the probe sonicator, and the tank was 1200 kg/h; about 25 W.Math.h/kg of energy is applied to the dispersion in the RPA at the dispersion stage (D); about 1.3 W.Math.h/kg is applied to the dispersion at the ultrasonic treatment stage (D); the mean tank residence time of the dispersion at a shear rate of about 1 s.sup.1 is about 3.25 minutes at the stage (R).

(97) The dispersion was produced by mixing the required proportions of water, carboxymethylcellulose Na salt, and SWCNTs and 6-fold dispersing in a NETZSCH Omega 500 high-pressure homogenizer at a pressure of 65 MPa and a dispersion transfer rate of 300 kg/h through the nozzle with a diameter of 700 m. The shear rate in the nozzle is about 6.Math.10.sup.5 s.sup.1. The power consumption was 9 kW, the specific input energy at the stage (D) was about 30 W.Math.h/kg. Between each two dispersion stages, the dispersion was held in a 100 liter tank at rest and agitated slowly by a gate agitator and at a shear rate of about 3 s.sup.1 for 20 minutes.

(98) The viscosity was measured at a constant temperature of 25 C. using a Brookfield DV2-TLV viscometer with an SC4-21 spindle. The viscosity as a function of shear rate is well described by the Ostwald-de Waele power law in a range from 0.093 s.sup.1 to 100 s.sup.1. The flow behavior index n is 0.26, and the flow consistency index is 12.8 Pa.Math.s.sup.0.26. The dispersion viscosity in the area of low shear rates of less than 1/6.3 s.sup.1 is more than 50 Pa.Math.s, and it is less than 1.5 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1.

(99) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 905 Pa, and the loss modulus G=240 Pa, which means that the dispersion is a highly viscous gel.

(100) The dispersion was used to produce the cathode slurry containing 49.6 wt. % of active cathode material LiFePO.sub.4 (LFP), 48.3 wt. % of water solvent, 1 wt. % of acetylene black, 1 wt. % of Na-carboxymethylcellulose gelling agent and binder, and 0.014 wt. % of single-walled carbon nanotubes. The cathode slurry was produced by the sequence of stages: mixing 1.7 g of the dispersion, 45 g of water, 1 g of Na-carboxymethylcellulose powder, 1 g of acetylene black, and 48 g of active component LFP (stage (C1) where water, an electrically conductive additive, and a binder were further introduced); agitating for 16 hours to produce a homogeneous slurry (stage C2).

(101) With both the single-walled and double-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant cathode slurry has a sharply pronounced dependence of viscosity on shear rate, which is well described by the power law. The flow behavior index is 0.27, and the flow consistency index is 14.4 Pa.Math.s.sup.0.27. The viscosity measured at a shear rate of 93 s.sup.1 is 0.51 Pa.Math.s, and the dependence extrapolation to a shear rate of 100 s.sup.1 gives a viscosity estimate of about 0.50 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of not more than 1 s.sup.1, the viscosity is at least 14.4 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(102) The storage stability of the cathode slurry was tested by the above method in Example 1. Within a week, the water content in the upper third of the slurry increased from 48.3 wt. % to 49.0 wt. %, i.e., less than 2 rel. % of the initial value. This is indicative of a high slurry stability.

(103) The dispersion was used to produce the anode slurry containing 45.9 wt. % of graphite active material, 53.1 wt. % of water solvent, 0.93 wt. % of Na-carboxymethylcellulose gelling agent, and 0.13 wt. % of single-walled carbon nanotubes. The anode slurry was produced by the sequence of stages: mixing 1.7 g of the dispersion and 55 g of water, 0.98 g of Na-CMC powder and 49 g of graphite powder (stage A1), and agitating the resultant mixture for 12 hours to produce a homogeneous slurry (stage A2).

(104) With both the single-walled and double-walled carbon nanotubes and the gelling agent in the dispersion used to produce the slurry, the resultant anode slurry has a sharply pronounced dependence of viscosity on shear rate, which is well described by the power law. The flow behavior index is 0.22, and the flow consistency index is 12.8 Pa.Math.s.sup.0.22. The viscosity measured at a shear rate of 93 s.sup.1 is 0.37 Pa.Math.s, and the dependence extrapolation to a shear rate of 100 s.sup.1 gives a viscosity estimate of about 0.35 Pa.Math.s, which provides process capacity for the application to the current collector plate. At shear rates of not more than 1 s.sup.1, the viscosity is at least 12.8 Pa.Math.s, which ensures the slurry stability during storage before use, and the stability of the slurry layer on the current collector before drying.

(105) The storage stability of the anode slurry was tested by the above method in Example 1. Within a week, the water content in the upper third of the slurry increased from 53.6 wt. % to 54.7 wt. %, i.e., less than 2 rel. % of the initial value. This is indicative of a high slurry stability.

(106) For the anode production, the resultant anode slurry was applied to a copper foil using a doctor blade, dried at a temperature of 100 C. for 1 hour and compacted on a calender with a force of 5 tons to an anode material density of 1.7 g/cm.sup.3. The anode properties were determined by assembling a cell with a Li cathode and the Li reference electrode, and an electrolyte, which is a 1 M solution of LiPF.sub.6 in the mixture of ethylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents with a volume ratio of 1:1:1 and additional 10% v/v of fluoroethylene carbonate. The initial specific capacity of the anode at a charge current of 0.1 A/g of the anode material is 330 mA.Math.h/g of the anode material.

(107) The lithium-ion battery was assembled from the resultant cathode and anode. A 16 m thick polypropylene separator was used. A 1.5 M solution of LiPF.sub.6 in the mixture of ethylene carbonate:ethyl methyl carbonate:dimethyl carbonate solvents in a volume ratio of 1:1:1 with additional 20% v/v of fluoroethylene carbonate was used as an electrolyte. The initial battery capacity at a discharge rate of 0.1 C was 1250 mA.Math.h. The battery capacity is 1130 mA h, i.e., more than 90% of the initial capacity, after 1000 cycles.

Example 8 (Comparative)

(108) The dispersion contains 0.4 wt. % of the SWCNTs described in Example 1, and water. The dispersion contains no gelling agent. The dispersion was produced similarly to Example 1.

(109) The dispersion viscosity was measured at a constant temperature of 25 C. using a Brookfield DV2-TLV viscometer with an SC4-21 spindle. The viscosity as a function of shear rate is described by the Ostwald-de Waele power law in a range from 0.093 s.sup.1 to 100 s.sup.1. The flow behavior index n is 0.62, and the flow consistency index is 3.0 Pa.Math.s.sup.0.62. The dispersion viscosity in the area of low shear rates of less than 1/6.3 s.sup.1 is about 6 Pa.Math.s, and it is about 1 Pa.Math.s in the area of shear rates of more than 18.6 s.sup.1. The dispersion viscosity in the area of low shear rates is less than 20 Pa.Math.s and is not enough to ensure dispersion stability during long-term storage.

(110) The rheological properties of the dispersion were measured with a HAAKE RheoStress 6000 dynamic shear rheometer in a plate-to-plate cell with a gap of 0.5 mm. The dispersion sample was transferred to the lower plate (d=20 mm) with a spatula, thermostatted at (T=19-21 C.), then the plates were closed to a gap of 0.55 mm, after which the excess sample was removed with a metal spatula, and the plates were closed again to a measurement gap of 0.5 mm. For a deformation amplitude of 1% corresponding to a rotation angle of the moving plate of 0.029, the storage modulus G is 103 Pa, the loss modulus G=19 Pa, which is also indicative of a fairly low viscosity of the resultant gel.

(111) The dispersion was used to produce the cathode slurry with its composition and production sequence similar to Example 1, except that there was no gelling agent in the dispersion. Therefore, the corresponding amount of gelling agent was added in the form of Na-carboxymethylcellulose solution: adding 54 g of the solution containing 1 g of Na-carboxymethylcellulose and 53 g of water to 12.5 g of the dispersion produced, mixing on an overhead stirrer for 30 minutes; mixing the resultant mixture with 97.75 g of the active component LiFePO.sub.4; adding 2.4 g of aqueous styrene butadiene rubber latex with a dry matter content of 50%; agitating for 16 hours to produce a homogeneous slurry.

(112) The viscosity of the resultant cathode slurry as a function of shear rate is illustrated by dark squares (curve 8C) in FIG. 3. This dependence is described by the Ostwald-de Waele power law with a flow behavior index n=0.46 and a flow consistency index 9.3 Pa.Math.s.sup.0.46. The slurry viscosity is about 9.3 Pa.Math.s at shear rates of about 1 s.sup.1. This viscosity, as shown by the slurry storage stability studies and cathode application experiments, is not enough to achieve the necessary technical result, which is no delamination of the cathode slurry during storage and high quality of the cathode obtained by applying the slurry to the current collector.

(113) The storage stability of the slurry was determined by the changing distribution of the solid particle content along the height of the slurry layer after the slurry storage in a 50 ml cylindrical test tube with a diameter of 30 mm. For this purpose, the slurry was put in the test tube, closed with a lid, and kept for 7 days under standard conditions (atmospheric pressure, 25 C.) and analyzed similarly to the procedure described in Example 1. A turbid supernatant layer of about 6 mm thickness was formed on the slurry surface in 7 days. For the cathode slurry of this Example, the solvent content in the initial slurry was 40 wt. %, after one-week storage, the solvent content was 54.1 wt. % in the upper third, 36.5 wt. % in the middle part, and 29.6 wt. % in the lower part. There was significant delamination of the cathode slurry preventing its application after 7 days.

(114) It is impossible to obtain a high-quality coating of the current collector with the cathode slurry when trying to produce a cathode with the resultant cathode slurrysee FIG. 4 (photo on the right). The resultant dispersion without a gelling agent, and the cathode slurry produced with the use of this dispersion do not allow the necessary technical result.

(115) The dispersion was used to produce the anode slurry with its composition and production sequence similar to Example 1, except that there was no gelling agent in the dispersion. Therefore, the corresponding amount of gelling agent was added in the form of Na-carboxymethylcellulose solution. The anode slurry was produced by the sequence of stages: mixing 187.5 g of the dispersion, 1388 g of water, 112 g of 1 wt. % of Na-CMC aqueous solution, 1000 g of graphite powder, and 454.2 g of silicon powder, agitating for 10 hours; adding 54 g of 50 wt. % of aqueous butadiene styrene latex suspension; agitating for 2 hours to produce a homogeneous slurry.

(116) The slurry storage stability was determined by a procedure similar to that described in Example 1. A turbid supernatant layer of about 8 mm thickness was formed on the slurry surface in 7 days. For the anode slurry of this Example, the solvent content in the initial slurry was 53.6 wt. %, after one-week storage, the solvent content was 68.1 wt. % in the upper third, 48.0 wt. % in the middle part, and 44.2 wt. % in the lower part. There was significant delamination of the cathode slurry preventing its application after 7 days.

(117) Table 1 below shows a summary of compositions and properties of dispersions of Examples 1-8.

(118) Table 2 below shows a summary of compositions and properties of cathode and anode slurries of Examples 1-8.

(119) TABLE-US-00001 TABLE 1 Gelling CNT/ Content of Viscosity Viscosity G G CNT agent (GA) GA mod. groups at at at at Example content content weight and metals K (1/6.3) s.sup.1 18.6 s.sup.1 1 Hz 1 Hz number wt. % wt. % ratio G/D wt. % Pa .Math. s.sup.n n Pa .Math. s Pa .Math. s Pa Pa 1 SWCNT 0.4 Na- 0.67 80 Cl: 0.24 9.0 0.14 43 0.72 912 190 CMC 0.6 Fe: 0.46 2 SWCNT 0.3 PVP 0.6 0.5 24 COOH: 0.62 21.6 0.16 102 1.9 2460 390 Fe: 0.006 3 SWCNT 0.3 Na-PAA 2 0.15 46 Fe: 14.2 19.0 0.23 79 0.52 1150 410 4 SWCNT and Na- 0.67 34 None 4.9 0.19 22 0.46 176 28 DWCNT 0.4 CMC 0.6 5 SWCNT 2 Li-CMC 10 80 Cl: 0.24 13.5 0.33 46 1.9 980 460 0.2 Fe: 0.46 6 SWCNT 0.3 Na-CMC 2 0.15 56 Fe: 0.4 20.5 0.13 102 1.6 2800 320 7 SWCNT 0.8 Na- 1 80 Cl: 0.24 12.8 0.26 50 1.47 905 240 CMC 0.8 Fe: 0.46 8 SWCNT 0.4 0 80 Cl: 0.24 3 0.62 6.0 1.0 103 19 (comp.) Fe: 0.46

(120) TABLE-US-00002 TABLE 2 Battery Cathode slurry Anode slurry capacity, % of Ex. Sta- K, Sta- K, initial one No. Content, wt. % bility Pa .Math. s.sup.n n Content, wt. % bility Pa .Math. s.sup.n n (after N cycles) 1 58.7 LFP, 40.0 water, + 21 0.26 31.3 graphite, 14.2 Si, + 11.6 0.17 90 (3000 cycles 0.72 SBR, 0.6 Na-CMC 53.6 water, 0.35 Na-CMC at 1 C) and 0.03 SWCNT 0.84 SBR, and 0.18 SWCNT 2 61 NCM111, 37.7 water, + 18.8 0.24 26.6 graphite, 16.2 Si, + 12.3 0.19 96 (1000 cycles 0.62 SBR, 0.62 Na-CMC, 55.5 water, 0.33 PVP, at 1 C) 0.047 PVP and 0.49 Na-CMC, 0.66 SBR and 0.023 SWCNT 0.17 SWCNT 3 29.9 LCO, 68.6 water, + 12.1 0.20 18.5 SiO.sub.x, 79.7 water, + 10.5 0.17 86 (215 cycles 1.25 Na-PAA 1.63 Na-PAA at 1 C) and 0.19 SWCNT and 0.24 SWCNT 4 58.7 LFP, 40.0 water, + 18.0 0.29 31.3 graphite, 14.2 Si, + 11.0 0.20 92 (400 cycles 0.72 SBR, 0.6 Na-CMC 53.6 water, 0.84 SBR, at 1 C) and 0.03 D&SWCNT 0.35 Na-CMC and 0.18 D&SWCNT 5 55.1 LFP, 42.3 water, + 19.9 0.18 18 graphite, 32.9 SiO.sub.x, + 20.4 0.17 96 (800 cycles 0.57 SBR, 1.22 Na-CMC 44.6 water, 3.1 Li-CMC, at 1 C) and 0.85 SWCNT 0.6 SBR and 0.9 SWCNT 6 66.1 NCM622, 2.2 water, + 22 0.28 39 graphite, 4.5 SiO.sub.x, + 11.6 0.25 85 (500 cycles 30.3 NMP, 0.046 Na- 55.1 water, 1.35 Na-CMC, at 0.33 C) CMC 1.32 PVDF and and 0.027 SWCNT 0.0069 SWCNT 7 49.6 LFP, 48.3 water, + 14.4 0.27 45.9 graphite, 53.1 water, + 12.8 0.22 90 (1000 cycles 1.0 carbon black, 0.93 Na-CMC at 0.5 C) 1.0 Na-CMC and 0.13 SWCNT and 0.014 SWCNT 8 58.7 LiFePO.sub.4, 40.0 water, 9.3 0.46 31.3 graphite, 14.2 Si, 6.9 0.41 low grade (comp.) 0.72 SBR, 0.6 Na-CMC 53.6 water, 0.35 Na-CMC, electrodes and 0.03 SWCNT 0.84 SBR and 0.18 SWCNT

INDUSTRIAL APPLICABILITY

(121) The present invention, in one embodiment, is used to produce dispersions of single-walled and/or double-walled carbon nanotubes and agglomerates thereof in a liquid phase, electrode slurries, lithium-ion battery electrodes, and lithium-ion batteries.

(122) It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention. The invention is further defined by the following claims.