PROCESS FOR MAKING AN (OXY)HYDROXIDE, AND (OXY)HYDROXIDE

Abstract

Disclosed herein is a process for making an (oxy)hydroxide of TM where TM refers to metals of which at least 97 mol-% are transition metals and where TM includes manganese and nickel, and where at least 50 mol-% of TM are manganese, the process including the steps of: (a) providing at least one aqueous solution () of water-soluble salts of such metals and an aqueous solution () including alkali metal hydroxide selected from the group consisting of NaOH and KOH, (b) combining solutions () and () at a pH value in the range of from 9.5 to 10.3, where such step (b) is carried out using at least one coaxial mixer including two coaxially orientated pipes through which an aqueous solution () and an aqueous solution of () are introduced into a stirred vessel, thereby precipitating an (oxy)hydroxide of TM, and (c) recovering and drying the (oxy)hydroxide of TM.

Claims

1. A process for making an (oxy)hydroxide of TM wherein TM refers to metals of which at least 97 mol-% are transition metals and wherein TM comprises manganese and nickel, and wherein at least 50 mol-% of TM are manganese, said process comprising the steps of: (a) providing at least one aqueous solution () of water-soluble salts of such metals and an aqueous solution () comprising alkali metal hydroxide selected from the group consisting of NaOH and KOH, (b) combining solutions () and () at a pH value in the range of from 9.5 to 10.3, wherein step (b) is carried out using at least one coaxial mixer comprising two coaxially orientated pipes through which an aqueous solution () and an aqueous solution of () are introduced into a stirred vessel, thereby precipitating an (oxy)hydroxide of TM, and (c) recovering and drying said (oxy)hydroxide of TM.

2. The process according to claim 1, wherein the outlet of the pipes of the coaxial mixer is below the level of liquid.

3. The process according to claim 1, wherein aqueous solution () is introduced through the inner pipe of the mixer and aqueous solution ) is introduced through the outer pipe.

4. The process according to claim 1, wherein, between steps (b) and (c), a step (b+) is performed including the transfer of slurry from step (b) to a second stirred vessel in which it is combined with solutions () and () at a pH value in the range of from 9.5 to 11.0 measured at 23 C., wherein step (c) is carried out in a continuous or semi-continuous mode, thereby further growing the (oxy)hydroxides of TM.

5. The process according to claim 1, wherein the drying in step (c) is performed at a temperature in the range of from 80 to 120 C.

6. The process according to claim 1, wherein the water-soluble salts of manganese and nickel in step (a) are the sulfates.

7. The process according to claim 1, wherein in certain intervals, the nozzle is flushed with water to physically remove transition metal (oxy)hydroxide incrustations.

8. The process according to claim 1, wherein TM contains metals according to formula (I) ##STR00007## where the variables are each defined as follows: M.sup.1 is at least one metal selected from the group consisting of Co, Ti, Zr, Nb, Ta, W, Sb, Sr, Al and Mg, a is a number in the range from 0.20 to 0.50, b is a number in the range from zero to 0.05, c is a number in the range from 0.50 to 0.80, and a+b+c=1.0.

9. A particulate metal (oxy)hydroxide according to general formula (II) ##STR00008## wherein TM refers to a combination of metals of which at least 97 mol-% are transition metals and wherein TM comprises manganese and nickel, and wherein at least 50 mol-% of TM are manganese, $0x<1,1<y2,\mathrm{and}0t0.1,$ wherein said particulate transition metal (oxy)hydroxide has an average secondary particle diameter D50 in the range of from 2 to 15 m, and wherein such secondary particles are agglomerated from primary particles that are essentially radially oriented, and wherein said metal (oxy)hydroxide displays reflections at 8.6 to 9.0 (a), 16.00 to 18.00 (b) and 21.40 to 22.00 2 (c) in X-ray diffraction analyses recorded with Cu-K-radiation.

10. The particulate metal (oxy)hydroxide according to claim 9, wherein TM corresponds to metals according to Ni.sub.aM.sup.1.sub.b Mn.sub.c wherein M.sup.1 is at least one metal selected from the group consisting of Co, Ti, Zr, Nb, Ta, W, Sb, Sr, Al and Mg, a is a number in the range from 0.20 to 0.50, b is a number in the range from zero to 0.05, c is a number in the range from 0.50 to 0.80, and a+b+c=1.0.

11. The particulate metal (oxy)hydroxide according to claim 9, having a specific surface according to BET in the range of from 2 to 50 m.sup.2/g.

12. The particulate metal (oxy)hydroxide according to claim 9, wherein the particle size distribution [(D90)(D10)] divided by (D50) is in the range of from 0.5 to 2.

13. The particulate metal (oxy)hydroxide according to claim 9, wherein the average form factor of secondary particles that is higher than 0.80 when determined by SEM imaging in 1000 magnification.

14. A method of using the particulate metal (oxy)hydroxides according to claim 9, the method comprising using the particulate metal (oxy)hydroxides for the manufacture of cathode active materials for lithium-ion batteries.

15. A process for making a cathode active material for a lithium-ion battery wherein said process includes the steps of (1) mixing at least one metal (oxy)hydroxide according to claim 9, with at least one compound of lithium selected from the group consisting of lithium hydroxide, lithium carbonate and lithium peroxide and, optionally, at least one oxide or (oxy)hydroxide or sulfate of Mg, Al, Ti, Zr, Nb, Ta, W or Mo, and (2) heating the mixture obtained from step (1) to 800 to 1000 C.

16. A particulate cathode active material according to the general formula Li.sub.1+kTM.sub.1kO.sub.2 wherein k is in the range of from 0.1 to 0.3, and wherein TM refers to a combination of metals of which at least 97 mol-% are transition metals and wherein TM comprises manganese and nickel, and wherein at least 50 mol-% of TM are manganese, wherein said particulate cathode active material has an average secondary particle diameter D50 in the range of from 2 to 15 m, and wherein such secondary particles are agglomerated from primary particles that are essentially radially oriented, and wherein such secondary particles have an average form factor that is higher than 0.80 when determined by SEM imaging in 1000 magnification.

17. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES/DRAWINGS

[0178] FIG. 1 shows top view SEM images of the inventive precursors TM-OH.1 (a, b) and TM-OH.2 (c, d). The top view SEM images of the comparative precursor C-TM-OH.3 are shown in panel (e) and (f).

[0179] For determination of the particle diameters, a Mastersizer 3000 from Malvern Panalytical GmbH was used. The sample was filled into the device until a light obscuration between 4.0-14.0% was achieved. The respective volume-based particle size distribution (PSD) was determined by laser diffraction based on Mie's scattering theory. A refractive index of 1.33 for H.sub.2O as dispersant was selected, while a refractive index of 2.19 of the solid phase was selected.

I. Manufacture of Precursors, TM-OH

[0180] Manufacturing examples, general remarks:

[0181] During all precipitation experiments the stirred vessel had a constant nitrogen overflow. The pH values refer to measurements at 23 C. [0182] Aqueous solution (.1): NiSO.sub.4 and MnSO.sub.4 (molar ratio of 1:2) with a total TM concentration of 1.65 mol/kg [0183] Aqueous solution (.1): aqueous NaOH solution (25 wt %)

I.1 Manufacture of Inventive Precursor TM-OH.1

[0184] The inventive precursor TM-OH.1 was made in a 2.4 L stirred vessel with a dosing unit comprising a coaxial mixer. In addition, the stirred vessel included an overflow system and a clarifier.

[0185] The stirrer consisted of a stirring shaft equipped with two four-bladed pitch blade turbines. The stirred vessel was charged with 2 L of deionized water and the temperature was set to 55 C. under constant stirring, energy uptake of (.sub.average6.3 W/L).

[0186] Aqueous solutions (.1) and (.1) were introduced into the stirred vessel through the coaxial mixer. The formation of a slurry was observed. The overall volume flow of solutions (.1) and (.1) was adjusted result in an average residence time of 5 h. During the reaction the pH value was set to 10.0 and kept constant by a pH regulation circuit adjusting the volume flow of solution (B. 1). The precipitation reaction was carried out in a continuous mode with a mother liquor withdrawal of 35% (through the clarifier with respect to the total volume flow). Through the overflow, resultant slurry was collected. The collected slurry contained about 400 g/L of TM-OH.1. TM-OH.1 was collected by filtration, washing with solution (.1) (1 kg of solution (.1) per kg of solid TM-OH. 1) and deionized water. Then, TM-OH.1 was dried at 120 C. for 14 hours.

I.2 Manufacture of Inventive Precursor TM-OH.2

[0187] Example I.1 was repeated with the exceptions that no mother liquor was withdrawn through the clarifier, and the stirring energy input was set to 5.4 W/L. The slurry withdrawn through the overflow system contained 120 g/l solids. TM-OH.2 was obtained.

I.3 Manufacture of the Comparative Precursor C-TM-OH.3

[0188] The manufacture of C-TM-OH.3 was carried out a 30 L stirred vessel without a coaxial mixer. The stirrer consisted out of a stirring shaft equipped with two four-bladed pitch blade turbines. Aqueous solutions (.1) and (.1) were introduced into the stirred vessel through separate dosing pipes. The formation of a slurry was observed. The overall volume flows of solutions (.1) and (.1) were adjusted resulting in an average residence time of 12 h. The pH value was set to 11.5 and was kept constant by a pH regulation circuit adjusting the volume flow of the solution (.1).

[0189] The slurry withdrawn through the overflow system contained 120 g/l solids. C-TM-OH.3 was collected by filtration, washing with solution (.1) (1 kg solution (.1) per kg of solid C-TM-OH.3.) and deionized water. Then, C-TM-OH.3 was dried at 120 C. for 14 hours.

[0190] SEM images of the resulting precursors TM-OH.1, TM-OH.2 and C-TM-OH.3 are shown in FIG. 1 and additional cross-sections are shown in FIG. 2.

TABLE-US-00001 TABLE 1 Summary of the physical properties of the inventive and comparative precursors BET D50/ Surface/ S content/ Form (I/I.sub.0) (I/I.sub.0) (I/I.sub.0) precursor m span m.sup.2/g wt % Factor reflection a reflection b reflection c TM-OH.1 6.7 1.57 31.0 0.24 0.82 1000 280 111 TM-OH.2 6.0 1.38 33.3 0.34 0.86 n.d. n.d. n.d. C-TM-OH.3 5.7 1.33 22.4 0.06 0.74 1000 196 73 n.d.: not determined
II. Synthesis of Cathode Active Materials from the Inventive and Comparative Precursors
II.1 Synthesis of Cathode Active Materials CAM.1 and CAM.2 from the Inventive Precursors TM-OH.1 and TM-OH.2

[0191] The respective cathode active material was synthesized from inventive precursor TM-OH.1 or TM-OH.2 by mixing the dried precursor with Li.sub.2CO.sub.3 and each 0.1 mol-% Zr(OH).sub.4 and TiO.sub.2, referring to the sum of Mn and Ni, in a molar ratio Li:(Ni+Mn+Ti+Zr) of 1.36:1. The resulting mixture was than filled into a crucible and heated up with 1.5 C./min to 950 C. and held at this temperature for 5 hours. Thereafter the obtained cathode active material (was cooled down to room temperature and was sieved using a 32 m sieve before the posttreatment was applied. Calcined materials were obtained.

[0192] For the purpose of a posttreatment, the respective calcined material were treated with a mixture of aqueous H.sub.2SO.sub.4 and Al.sub.2(SO.sub.4).sub.3. 100 g of water, 200 g of 0.4 M H.sub.2SO.sub.4 and 37 mol Al.sub.2(SO.sub.4).sub.3 were added to 100 g of the respective calcined material and stirred for 30 min. After filtration the CAM was washed with washing medium (water:calcined material 4:1), filtered and dried under vacuum. Finally, the so treated material was reannealed for 5 hours at 400 C. with a heating ramp of 3 C./min resulting in CAM.1 or CAM.2, respectively. A cross section SEM image of an CAM.1 is shown in FIG. 3.

II.2. Synthesis of the Comparative Cathode Material from the Comparative Precursor C-TM-OH.3

[0193] Comparative cathode active material C-CAM.3 was synthesized from the inventive precursors C-TM-OH.3 by mixing the dried precursor with Li.sub.2CO.sub.3, each 0.1 mol-% Zr(OH).sub.4 and TiO.sub.2, referring to the sum of Mn and Ni, in a molar ratio Li:(Ni+Mn+Ti+Zr) of 1.36:1. The resulting mixture was than filled into a crucible and heated up with 1.5 C./min to 950 C. and held at this temperature for 6 h. Thereafter the obtained calcined material was cooled down to room temperature and was sieved using a 32 m sieve before the posttreatment was applied.

[0194] For the purpose of a posttreatment the calcined material was treated with a mixture of aqueous H.sub.2SO.sub.4 and Al.sub.2(SO.sub.4).sub.3. 100 g of water, 200 g of 0.4M H.sub.2SO.sub.4 and 37 mol Al.sub.2(SO.sub.4).sub.3 were added to 100 g of the comparative calcined material and stirred for 30 min. After filtration the CAM was washed with washing medium (water:calcined material=4:1), filtered and dried under vacuum. Finally, the so treated material was reannealed for 5 hours at 400 C. with a heating ramp of 3 C./min leading to the comparative cathode active material C-CAM.3.

TABLE-US-00002 TABLE 2 Summary of the physical properties of the resulting CAMs d.sub.50 BET Surface Pressed Form CAM [m] span [m.sup.2/g] density kg/l factor CAM.1 7.0 1.83 5.9 3.02 0.89 CAM.2 5.8 1.80 6.1 2.82 0.81 C-CAM.3 5.4 1.44 4.8 2.95 n.d. The pressed density was determined at a pressure of 250 MPa

III. Preparation of Electrodes, Electrolyte and Electrochemical Evaluation of the Inventive and Comparative Cathode Active Materials

III.1 Electrode Preparation

[0195] Electrodes having the following composition: 94% cathode active material (CAM), 3% conductive agent (Super C65) and 3% the polymeric binder (polyvinylidene fluoride (PVDF), Solef 5130), were prepared by dissolving the binder in N-methyl-2-pyrrolidone and adding the conductive agent. The resulting slurry was dispersed in a planetary centrifugal mixer (ARE-250, Thinky Corp.; Japan), before the respective CAM was added and the resulting mixture was dispersed again using the same device as mentioned before to obtain a homogeneous slurry. Subsequently the slurry was cast onto aluminum foil using the doctor blade technique. After drying, circular electrodes circular electrodes with a diameter of 1.4 cm were punched out and dried at 120 C. under reduced pressure of 10-3 mbar for 12 hours. The mass loading was adjusted to equal 15 mg/cm.sup.2.

III.2 Electrolyte Manufacture

[0196] A base electrolyte composition containing 12.7 wt % of LiPF.sub.6, 26.2 wt % of ethylene carbonate (EC), and 61.1 wt % of ethyl methyl carbonate (EMC) (EL base 1), based on the total weight of EL base 1 was prepared, before to this base electrolyte formulation 2 wt. % of vinylene carbonate (VC) was added resulting into the final composition EL base 2 used in the electrochemical evaluation of the electrodes based on the inventive and comparative CAMs.

III.3 Cell Preparation and Electrochemical Evaluation

[0197] Coin-type half cells (20 mm in diameter and 3.2 mm in thickness) comprising a cathode prepared as described in III.1 as working electrode and lithium metal counter electrode, were assembled and sealed in an Ar-filled glove box. In addition, the cathode and anode and a separator were superposed in order of cathode//separator//Li foil to produce a half coin cell. Thereafter, 0.15 ml of the EL base 2 which is described above (III.2) were introduced into the coin cell. Electrochemical testing of the aforementioned coin cells was conducted on a Maccor 4000 battery cycler with 3.0 and 4.7 V (4.8 V in the activation cycle (first cycle) as lower and upper cut-off voltages, respectively. After the activation within the first cycles a C-rate test was employed to elucidate the rate capability of the CAM range from 0.2-3 C. After the C-rate test the electrodes were cycled with 0.5 C in the constant current constant voltage (CCCV) mode Table 3 gives a detailed summary of the different C-rates of the testing protocol.

TABLE-US-00003 TABLE 3 Overview of the used electrochemical evaluation protocol Cycle C-rate charge/discharge.sup.a Mode 1 0.067C CCCV 2 0.1C CCCV 4 every 5% SOC DCIR 5 0.20, 0.5C CCCV 9 0.5C/1C CCCV 11 0.5C/2C CCCV 13 0.5C/3C CCCV 15 0.5C CCCV 17 every 5% SOC DCIR 18 0.5C CCCV 69 every 5% SOC DCIR 70 0.5C CCCV 121 every 5% SOC DCIR

[0198] The stop criteria of constant voltage-step within the CCXCV mode was either a CV step for 1 h or a total current reaching 0.02 C

TABLE-US-00004 TABLE 4 Overview of the electrochemical performance of the inventive CAMs CAM.1, CAM.2 and the comparative C-CAM.3. Initial Rate Performance Capacity & Retention DC/ CE/ 1 C/ 2 C/ 3 C/ Q1/ Q50/ Q50/Q1/ CAM mAh g.sup.1 % mAh g.sup.1 mAh g.sup.1 mAh g.sup.1 mAh g.sup.1 mAh g.sup.1 % CAM.1 269.5 93.3 223.1 207.9 191.2 227.1 210.7 92.8 CAM.2 266.9 92.6 215.9 201.4 188.7 218.7 204.8 93.6 C-CAM.3 268.8 92.5 212.6 181.4 120.5 225.3 204.4 90.7