COMPOSITE MATERIAL, THE METHOD OF ITS PREPARATION AND APPLICATION THEREOF

Abstract

A stressed composite material is disclosed, characterized in that it contains Li.sub.4Ti.sub.5O.sub.12 spinel nanocrystallites in an amount of 25-93% by weight, encapsulated during the pyrolysis process in a tightly adherent and conductive carbon aerogel matrix with a carbon content of 7-74% by weight, with a specific surface area of the composite of 44-426 m.sup.2/g, and a pore volume of the composite of 0.03-0.21 cm.sup.3/g, and an average pore size of the composite of 2-3 nm. Also disclosed is a method for obtaining the stressed composite material and an application of the stressed composite material for manufacturing electrode materials and lithium-ion cells.

Claims

1. A composite material, characterized in that it contains a matrix formed by carbon aerogel and Li.sub.4Ti.sub.5O.sub.12 spinel nanocrystallites dispersed in this matrix, with a carbon content in the composite of 7-74% by weight and a content of Li.sub.4Ti.sub.5O.sub.12 spinel nanocrystallites in the composite of 25-93% by weight, with a specific surface area of the composite of 44-426 m.sup.2/g and a pore volume of the composite of 0.03-0.21 cm.sup.3/g, and an average pore size of the composite of 2-3 nm.

2. The composite of claim 1, wherein the Li.sub.4Ti.sub.5O.sub.12 nanocrystallites have a size in the range of 40-70 nm.

3. A method of obtaining composite material, characterized in that an aqueous suspension containing Li.sub.4Ti.sub.5O.sub.12 in the amount of 5-75% by weight and potato starch in the amount of 25-95% by weight undergoes a polycondensation process at 60-90 C., and then the obtained hydrogel undergoes an aging process, followed by a solvent exchange using an aqueous alcohol solution, and then the obtained alkogel is dried, and the dried gel is subjected to pyrolysis at 600-900 C.

4. The method of claim 3, wherein the polycondensation is carried out preferably at a temperature of up to 85 C.

5. The method of claim 3, wherein the polycondensation is carried out until a gel is obtained.

6. The method of claim 3, wherein the aging process is carried out for not less than 24 h.

7. The method of claim 3, wherein the aging process is carried out at room temperature and at atmospheric pressure.

8. The method of claim 3, wherein the solvent exchange process is carried out using an aqueous alcohol solution with a concentration in the range of 10-99.8%.

9. The method of claim 3, wherein an alcohol selected from the group including methanol, ethanol, propanol or a mixture thereof of any composition is used as the alcohol.

10. The method of claim 3, wherein that the pyrolysis is carried out under inert gas conditions or under reducing gas conditions.

11. The method of claim 10, wherein a gas selected from the group including nitrogen, argon, helium or a mixture of these gases of any composition is used as the inert gas.

12. (canceled)

13. A method of manufacturing an electrode material or a lithium-ion cell, the method comprising: providing the composite material of claim 1; and forming the composite material into an electrode or incorporating the composite material into a lithium-ion cell.

Description

EXAMPLE 1

Parameters of Commercially Available Li.sub.4Ti.sub.5O.sub.12 (LTO) Given by the Manufacturer (MTI Corporation): [0027] grain size: 0.2-34.0 m, [0028] conductivity: 2.Math.10-5 S/cm, [0029] specific surface area: 9.0-13.0 m.sup.2/g, [0030] density 0.9 m.sup.2/g.

[0031] In order to obtain the CAG/LTO 5 composite material, an aqueous suspension of commercial lithium-titanium oxide powder Li.sub.4Ti.sub.5O.sub.12, LTO (manufacturer MTI, >98%) and potato starch PS (Sigma Aldrich) with a weight ratio of LTO:PS 5:95 was prepared in a ratio of 10% by weight of the LTO and PS mixture and 90% by weight of distilled water. The prepared suspension was then placed in an oil bath and heated to 85 C. with constant stirring. The whole mixture was left in the bath for about 30 minutes from the time of pasting. After this time, the obtained sol was removed from the bath and aged for 24 h, leaving it in the air at room temperature. After aging, the obtained gel was covered with ethanol solution (manufacturer Borzcin, 96% v/v) and set aside sealed with parafilm for 5 days for solvent exchange. Any alcohol chosen from the group including: methanol, ethanol, propanol can be used in the solvent exchange process. The resulting alkogel was dried in an oven for 24 h at 50 C. under atmospheric pressure. The organic aerogel obtained after drying was sequentially pyrolyzed in a tube furnace for 6 h at 700 C. (temperature build-up rate of 2 C./min) and in argon atmosphere (Air Products, 99.999%). The inert gas in the pyrolysis process can be argon, nitrogen, helium or a mixture of these gases of any composition. The pyrolysis process can also be carried out under reducing gas conditions. After pyrolysis, the composite, which was in the form of a monolith, was ground into powder using an agate mortar.

[0032] The resulting composite had an elemental carbon content of 74% by weight of the whole composite, while LTO in the composite accounted for 25%. The content of other elements (hydrogen and nitrogen) was determined as 1%. The size of LTO crystallites in the composite determined from the Scherrer equation was 47 nm. The specific surface area determined by N.sub.2-BET low-temperature nitrogen sorption measurements reached 425.4 m.sup.2/g, the pore volume was 0.201 cm.sup.3/g, and the average pore size was 2 nm.

[0033] Electrochemical tests in the range of 0.001-3.0 V showed that the resulting composite had a gravimetric capacity of: 281 mAh/g after 11 cycles at C/5 current load, 208 mAh/g after 31 cycles at 1 C current load, 78 mAh/g after 71 cycles at 20 C current load, and 224 mAh/g after 81 cycles at 1 C current load.

EXAMPLE 2

[0034] The CAG/LTO 25 composite material was prepared similarly to Example 1, with the LTO:PS weight ratio of the starting mixture being 25:75.

[0035] The resulting composite had an elemental carbon content of 31% by weight of the whole composite, while LTO in the composite accounted for 69%. The content of other elements (hydrogen and nitrogen) was negligible. The size of LTO crystallites in the composite determined from the Scherrer equation was 43 nm. The specific surface area determined by N.sub.2-BET low-temperature nitrogen sorption measurements reached 180.4 m.sup.2/g, the pore volume was 0.107 cm.sup.3/g, and the average pore size was 2 nm.

[0036] Electrochemical tests in the range of 0.001-3.0 V showed that the resulting composite had a gravimetric capacity of: 243 mAh/g after 11 cycles at C/5 current load, 214 mAh/g after 31 cycles at 1 C current load, 118 mAh/g after 71 cycles at 20 C current load, and 214 mAh/g after 81 cycles at 1 C current load.

EXAMPLE 3

[0037] The CAG/LTO 50 composite material was prepared similarly to Example 1, with the LTO:PS weight ratio of the starting mixture being 50:50.

[0038] The resulting composite had an elemental carbon content of 16% by weight of the whole composite, while LTO in the composite accounted for 84%. The content of other elements (hydrogen and nitrogen) was negligible. The size of LTO crystallites in the composite determined from the Scherrer equation was 55 nm. The specific surface area determined by N.sub.2-BET low-temperature nitrogen sorption measurements reached 107.5 m.sup.2/g, the pore volume was 0.083 cm.sup.3/g, and the average pore size was 3 nm.

[0039] Electrochemical tests in the range of 0.001-3.0 V showed that the resulting composite had a gravimetric capacity of: 264 mAh/g after 11 cycles at C/5 current load, 240 mAh/g after 31 cycles at 1 C current load, 157 mAh/g after 71 cycles at 20 C current load, and 244 mAh/g after 81 cycles at 1 C current load.

EXAMPLE 4

[0040] The CAG/LTO 75 composite material was prepared similarly to Example 1, with the LTO:PS weight ratio of the starting mixture being 75:25.

[0041] The resulting composite had an elemental carbon content of 7% by weight of the whole composite, while LTO in the composite accounted for 93%. The content of other elements (hydrogen and nitrogen) was negligible. The size of LTO crystallites in the composite determined from the Scherrer equation was 66 nm. The specific surface area determined by N.sub.2-BET low-temperature nitrogen sorption measurements reached 44.5 m.sup.2/g, the pore volume was 0.031 cm.sup.3/g, and the average pore size was 3 nm.

[0042] Electrochemical tests in the range of 0.001-3.0 V showed that the resulting composite had a gravimetric capacity of: 224 mAh/g after 11 cycles at C/5 current load, 210 mAh/g after 31 cycles at 1 C current load, 151 mAh/g after 71 cycles at 20 C current load, and 212 mAh/g after 81 cycles at 1 C current load.

EXAMPLE 5

[0043] A CAG/LTO material was prepared that was a physical mixture of commercial lithium-titanium oxide powder Li.sub.4Ti.sub.5O.sub.12, LTO (MTI, >98%) and a carbon aerogel based on potato starch PS (Sigma Aldrich) in a LTO:CAG weight ratio of 84:16.

[0044] The resulting composite had an elemental carbon content of 16% by weight of the whole composite, while LTO in the composite accounted for 84%. The content of other elements (hydrogen and nitrogen) was negligible. The specific surface area determined by N.sub.2-BET low-temperature nitrogen sorption measurements reached 84.8 m.sup.2/g, the pore volume was 0.044 cm.sup.3/g, and the average pore size was 2 nm.

[0045] Electrochemical tests in the range of 0.001-3.0 V showed that the resulting composite had a gravimetric capacity of: 96 mAh/g after 11 cycles at C/5 current load, 60 mAh/g after 31 cycles at 1 C current load, 9 mAh/g after 71 cycles at 20 C current load, and 57 mAh/g after 81 cycles at 1 C current load.

EXAMPLE 6

[0046] A CB/LTO composite material was prepared that was a physical mixture of commercial Li.sub.4Ti.sub.5O.sub.12 lithium-titanium oxide powder, LTO (MTI, >98%) and commercial carbon black CB conductive additive (Alfa Aesar, Super PR Conductive, 99+%, metals basis) in a LTO: CB weight ratio of 84:16.

[0047] The resulting composite had an elemental carbon content of 16% by weight of the whole composite, while LTO in the composite accounted for 84%. The content of other elements (hydrogen and nitrogen) was negligible.

[0048] Electrochemical tests in the range of 0.001-3.0 V showed that the resulting composite had a gravimetric capacity of: 238 mAh/g after 11 cycles at C/5 current load, 224 mAh/g after 31 cycles at 1 C current load, 159 mAh/g after 71 cycles at 20 C current load, and 223 mAh/g after 81 cycles at 1 C current load.

EXAMPLE 7

[0049] A material representing only pure commercial Li.sub.4Ti.sub.5O.sub.12 lithium-titanium oxide powder, LTO (MTI, >98%), was prepared.

[0050] The size of LTO crystallites determined from the Scherrer equation was 70 nm. The specific surface area determined by N.sub.2-BET low-temperature nitrogen sorption measurements reached 8.5 m.sup.2/g, the pore volume was 0.016 cm.sup.3/g, and the average pore size was 8 nm.

[0051] Electrochemical tests in the range of 0.001-3.0 V showed that the resulting composite had a gravimetric capacity of: 73 mAh/g after 11 cycles at 5 C current load, 42 mAh/g after 31 cycles at 1 C current load, 2 mAh/g after 71 cycles at 20 C current load, and 43 mAh/g after 81 cycles at 1 C current load.

EXAMPLE 8

[0052] Fabrication of electrodes from the material obtained according to examples 1-7 and assembly of the cell.

[0053] For the preparation of electrodes, the obtained composites according to examples 1-7 were mixed with a binder (polymer binder), which was poly(vinylidene fluoride), PVDF (Sigma-Aldrich) at a weight ratio of composite material to PVDF of 9:1. The prepared mixture was then suspended in N-Methylpyrrolidone, NMP (Sigma Aldrich, 99.5%) and homogenized in a ball mill at a stirring speed of 750 rpm for two 2-minute cycles with a 1-minute interval in between. The resulting slurries were spread on previously cleaned copper foils, which were current collectors, using a knife on an automatic thin film preparation table. The slurries applied to the foils were further dried for 24 hours at 90 C. under atmospheric pressure. After drying, 12-mm-diameter disks with the applied composite material were cut from each foil and used as electrodes.

[0054] The cells were assembled in R-2032 type housings (so-called coin cells) in a glove box (UNILAB with circulator, MBRAUN), under an oxygen-free and anhydrous atmosphere. Each cell contained a metallic lithium reference electrode, separated from the test electrode by a Celgard 2325 polymer membrane assembled with two Whatman GF/F glass fiber membranes. The electrolyte was a 1 M solution of LiPF.sub.6 salt in a mixture of ethylene carbonate EC and diethyl carbonate DEC in a volume ratio of 1:1, which was introduced into the cell by saturating the used separators with it.

COMPARATIVE EXAMPLE 1

[0055] Li Wang, Zonglin Zhang, Guangchuan Liang, Xiuqin Ou, Yingqiu Xu; Synthesis and electrochemical performance of Li.sub.4Ti.sub.5O.sub.12/C composite by a starch sol assisted method, Powder Technology, 215-216, 2012, 79-84.

[0056] Stoichiometric amounts of TiO.sub.2 (anatase) and Li.sub.2CO.sub.3 (molar ratio Li:Ti=4.2:5), as well as starch (starch:Li.sub.4Ti.sub.5O.sub.12=5; 7.5; 10; 12.5; 15% by weight) were used to obtain Li.sub.4Ti.sub.5O.sub.12/C starch composites. Starch was mixed with an appropriate amount of distilled water (the exact volume of water was not specified in the cited article), and then heated at 80 C. until a homogeneous, transparent sol was obtained. Subsequently, a mixture of TiO.sub.2 and Li.sub.2CO.sub.3 was added to the above suspension, with constant heating and stirring of the system, until a white gel was obtained. The resulting product was dried at 120 C. and then subjected to a two-step pyrolysis process in a tube furnace under a stream of nitrogen. In the first step, the precursor was pyrolyzed at 600 C. for 4 h, and in the second step at 800 C. for 6 h. The resulting Li.sub.4Ti.sub.5O.sub.12/C composite was cooled to room temperature and ground.

[0057] The studied Li.sub.4Ti.sub.5O.sub.12/C materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and charge/discharge tests (CELL TEST). Diffractograms of the obtained Li.sub.4Ti.sub.5O.sub.12/C composites (with different starch contents) confirm that the studied materials have the crystalline structure of the Li.sub.4Ti.sub.5O.sub.12 spinel, and that the addition of carbon present does not cause changes in their structure (low amorphous carbon content).

[0058] The average size of the crystallites and the lattice constant were not determined in the article. Using thermogravimetric analysis, the actual carbon content was determined Li.sub.4Ti.sub.5O.sub.12/C composites with starch contents of 5.0; 7.5; 10.0; 12.5 and 15.0% by weight have 1.03; 2.19; 3.21; 4.37 and 5.18% by weight of carbon, respectively. As the carbon content increased, the colour of the test samples became darker. Li.sub.4Ti.sub.5O.sub.12/C composites with lower starch content (5.0 and 7.5%) were characterized by a smooth surface with relatively large grain sizes. In contrast, composites with higher starch contents (10.0; 12.5 and 15.0%) had a more rough surface at the same time with smaller grain sizes. The Li.sub.4Ti.sub.5O.sub.12/C composite with 3.21% carbon content had an average particle size in the range of 200-300 nm. As the carbon content increased, agglomerates appeared in the samples.

[0059] To prepare the electrodes, the Li.sub.4Ti.sub.5O.sub.12/C active material was mixed with carbon additiveacetylene black and binderpolytetrafluoroethylene (PTFE) in a mass ratio of 80:15:5. The electrochemical cells were assembled in a glove box under argon atmosphere. Pure lithium was used as the reference electrode, Celgard 2400 microporous polyethylene membrane as the separator and 1 M solution of LiPF.sub.6 in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC), in a volume ratio of 1:1 as the electrolyte. The cells were left after assembly for at least 5 hours. Charge/discharge tests were carried out in the potential range of 1.0-2.5 V (vs. Li/Li.sup.+), at room temperature, with different current loads: 0.2 C (C/5); 1 C; 2 C and 5 C. Discharge capacity under 0.2 C load for materials with carbon content of 1.03; 2.19; 3.21; 4.37 and 5.18% were: 155.6; 160.9; 168.5; 165.0 and 161.9 mAh/g, respectively. The highest discharge capacity was achieved by the composite with a carbon content of 3.21% (168.5 mAh/g). As the current increased, the discharge capacity for this composite decreased from 168.5 (0.2 C) to 160.8 (1 C), 155.1 (2 C) and 141.8 mAh/g (5 C). Moreover, under 1 C load, after 25 cycles of operation, its capacity decreased from 159.8 to 157.2 mAh/g.

COMPARATIVE EXAMPLE 2

[0060] Z. Wang, G. Xie, L. Gao; Electrochemical Characterization of Li.sub.4Ti.sub.5O.sub.12/C Anode Material Prepared by Starch-Sol-Assisted Rheological Phase Method for Li-Ion Battery, Journal of Nanomaterials, 2012, 2012, 4545-4557.

[0061] Starch (3.0 g starch/0.02 mole Li.sub.4Ti.sub.5O.sub.12) was mixed with an appropriate amount of deionized water (the exact volume of water was not specified in the cited article). The resulting mixture was heated in an oil bath at 110 C. until a transparent suspension was obtained. Subsequently, the starch paste was mixed with a stoichiometric amount of LiOH and TiO.sub.2 (molar ratio Ti: Li=4.2:5). The thick suspension was transferred to a tube furnace and reheated at a rate of 15/min to 850 C. under nitrogen atmosphere, and then sintered at this temperature for 4 h. The resulting Li.sub.4Ti.sub.5O.sub.12/C composite was cooled to room temperature and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and charge/discharge tests (CELL TEST).

[0062] The diffractogram of the obtained Li.sub.4Ti.sub.5O.sub.12/C composite confirms that it has the crystalline structure of the Li.sub.4Ti.sub.5O.sub.12 spinel (space group Fd3m), and the carbon addition present in it does not cause changes in its structure (low amorphous carbon content). The average crystallite size calculated from the Scherrer equation was 400600 nm, and the lattice constant was 8.359 . Using thermogravimetric analysis, the actual carbon content, i.e. 5%, was determined. The resulting powder was grey in colour. The carbon uniformly covered the surface of the LTO grains, forming a layer of 5 nm. Li.sub.4Ti.sub.5O.sub.12/C particles had a relatively low degree of agglomeration, and their average size was about 500 nm.

[0063] To prepare the electrodes, 84% by weight of the active material (Li.sub.4Ti.sub.5O.sub.12/C), 10% by weight of a conductive additive (super-P-Li carbon black) and a binder containing: 3% by weight of CMC (sodium salt of carboxymethylcellulose) and 3% by weight of SBR (styrene-butadiene rubber) were mixed using deionized water as a solvent. The suspension was dispersed and then spread evenly on aluminum foil. The electrodes thus obtained were dried under vacuum at 100 C. for 24 h. Coin cells were assembled in a glove box under argon atmosphere. Pure lithium was used as the reference electrode, Celgard 2320 microporous polyethylene membrane as the separator and 1.3 M solution of LiPF.sub.6 in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:3 mass ratio as the electrolyte. Charge/discharge tests were carried out in the potential range of 1.0-2.0 V (vs. Li/Li.sup.+), at room temperature, at various current intensities. At a load of 0.2 C (C/5), the initial discharge capacity of the composite was 171.5 mAh/g. The voltage curves were characterized by a flat plateau of about 1.55 V (vs. Li/Li.sup.+). For 1 C load, the initial discharge capacity of Li.sub.4Ti.sub.5O.sub.12/C was 168.6 mAh/g, retaining 87% of its value after 500 operation cycles. In contrast, for 20 C load, the initial discharge capacity was 110 mAh/g, with no apparent decrease in capacity observed in the first 1000 cycles (only after 2000 cycles did the material reach 73% of its initial capacity).

COMPARATIVE EXAMPLE 3

[0064] P. Liu, Z. A. Zhang, J. Li, Y. Q. Lai; Effects of carbon sources on electrochemical performance of Li.sub.4Ti.sub.5O.sub.12/C composite anode materials, Journal of Central South University of Technology, 17 (6), 2010, 1207-1210.

[0065] Li.sub.4Ti.sub.5O.sub.12 and 2% by weight of starch were mixed with an appropriate amount of ethanol (the exact volume and concentration of ethanol were not specified in the cited article), and then milled in a mill for 2 h. The mixture was then dried at 120 C. for 8 h. The resulting powder was placed in a tube furnace for sintering it at 800 C. for 6 h under nitrogen atmosphere. The Li.sub.4Ti.sub.5O.sub.12/C composite was cooled to room temperature and characterized by X-ray diffraction (XRD) and charge/discharge tests (CELL TEST).

[0066] The diffractogram of the obtained Li.sub.4Ti.sub.5O.sub.12/C composite confirms that it has the crystalline structure of the Li.sub.4Ti.sub.5O.sub.12 spinel (space group Fd3m), and the carbon addition present in it does not cause changes in its structure (low amorphous carbon content). The average crystallite size and lattice parameter were not determined. The actual carbon content was not determined. The resulting powder was dark grey/black in colour.

[0067] In order to prepare the electrodes, the Li.sub.4Ti.sub.5O.sub.12/C active material was mixed with a carbon additivecarbon black and a binderpolyvinylidene fluoride (PVDF) in a mass ratio of 80:10:10. The mixture was milled using N-methyl-2-pyrrolidone (NMP) as a solvent. The suspension was spread evenly on copper foil. The electrodes thus obtained were dried under vacuum at 120 C. for 24 h. Coin cells were assembled in a glove box under argon atmosphere. Pure lithium was used as the reference electrode, Celgard 2400 microporous polyethylene membrane as the separator and 1 M solution of LiPF.sub.6 in a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) in a mass ratio of 1:1:1 as the electrolyte. Charge/discharge tests were conducted in the potential range of 0.8-2.5 V (vs. Li/Li.sup.+), at room temperature. Voltage curves were characterized by a flat plateau at about 1.53-1.57 V (vs. Li/Li.sup.+). The initial discharge capacity of Li.sub.4Ti.sub.5O.sub.12/C under 0.1 C (C/10) load was 159.0 mAh/g.

COMPARATIVE EXAMPLE 4

[0068] B. Prihandoko, A. Subhan, S. Priyono; Electrochemical Behavior of Li.sub.4Ti.sub.5O.sub.12 under In Situ Process of Sintering and Surface Coating with Cassava Powder, Advanced Materials Research, 789, 2013, 21-27.

[0069] LTO was prepared by powder metallurgy using TiO.sub.2 and LiOH H.sub.2O as raw materials. Stoichiometric amounts were measured (the exact weights were not specified in the cited article), and the mixture was calcined at 700 C. for 1 h. The resulting material was mixed with tapioca flour (as the carbon source) in a 1:1 ratio and then pyrolyzed under nitrogen atmosphere. The thermal treatment process was carried out at 800 and 850 C. for 1 hour. The obtained Li.sub.4Ti.sub.5O.sub.12/C composites were characterized by X-ray diffraction (XRD), scanning electron microscopy with integrated energy dispersive X-ray spectrometer (SEM-EDX) and cyclic voltammetry (CV).

[0070] Diffractograms of the obtained Li.sub.4Ti.sub.5O.sub.12/C composites confirm that the studied materials have the crystalline structure of the Li.sub.4Ti.sub.5O.sub.12 spinel, and the addition of carbon present in the composite does not cause changes in the structure (low amorphous carbon content). In the sample sintered at 800 C., an impurity appearedanatase phase coming from the raw material. In the 850 C. sample, the presence of TiO.sub.2 was very small. The average crystallite size and lattice parameter were not determined. On the basis of EDX analysis, the actual carbon content25.3 and 11.1% by weightwas determined for the materials sintered at 800 and 850 C., respectively. The obtained powders were black in colour. The carbon coating on the surface of the grains had a porous morphology. The article does not include information on the method of electrode preparation. Electrochemical characteristics were determined by cyclic voltammetry measurements. The Li.sub.4Ti.sub.5O.sub.12/C composite prepared by sintering at 850 C. had an operating voltage of 1.55 V and a capacity of about 5 mAh/g.

TABLE-US-00001 TABLE 1 Test results for the materials of Examples 1-7 Specific capacity vs. Li/Li+ in the potential range of LTO Specific Average 0.001-3.0 V [mAh/g] Carbon LTO crystallite surface Pore pore after 11 after 31 after 71 after 81 content content size area volume size cycles cycles cycles cycles Example Sample [%] [%] [nm] [m.sup.2/g] [cm.sup.3/g] [nm] (C/5) (1 C) (20 C) (1 C) 1 CAG/LTO 5 74 25 47 425.4 0.201 2 281 208 78 224 composite 2 CAG/LTO 25 31 69 43 180.4 0.107 2 243 214 118 214 composite 3 CAG/LTO 50 16 84 55 107.5 0.083 3 264 240 157 244 composite 4 CAG/LTO 75 7 93 66 44.5 0.031 3 224 210 151 212 composite 5 CAG/LTO 16 84 84.8 0.044 2 96 60 9 57 physical mixture 6 CB/LTO 16 84 238 224 159 223 physical mixture 7 pure LTO 0 100 70 8.5 0.016 8 73 42 2 43 commercial material

TABLE-US-00002 TABLE 2 Test results for the materials of Comparison example 1 Specific capacity vs. Li/Li+ LTO Specific Average in the potential range of Carbon LTO crystallite surface Pore pore 1-2.5 V [mAh/g] content content size area volume size (0.2 (1 (2 (5 Example Sample [%] [%] [nm] [m.sup.2/g] [cm.sup.3/g] [nm] C) C) C) C) 1 LTO/C 5 1.03 95 155.6 2 LTO/C 7.5 2.19 92.5 160.9 3 LTO/C 10 3.21 90 200-300 168.5 160.8 155.1 141.8 4 LTO/C 12.5 4.37 87.5 165.0 5 LTO/C 15 5.18 85 161.9

TABLE-US-00003 TABLE 3 Test results for the materials of Comparison example 2 Specific capacity vs. Li/Li+ LTO Specific Average in the potential range of Carbon LTO crystallite surface Pore pore 1-2.0 V [mAh/g] content content size area volume size (0.2 (1 (20 Example Sample [%] [%] [nm] [m.sup.2/g] [cm.sup.3/g] [nm] C) C) C) 1 LTO/C 5 0.02 400-600 171.5 168.6 110.0

TABLE-US-00004 TABLE 4 Test results for the materials of Comparison example 3 LTO Specific Average Specific capacity vs. Li/Li+ Carbon LTO crystallite surface Pore pore in the potential range of content content size area volume size 0.8-2.5 V [mAh/g] Example Sample [%] [%] [nm] [m.sup.2/g] [cm.sup.3/g] [nm] Initial discharge capacity (0.1 C) 1 LTO/C 2% 98 154.3 glucose 2 LTO/C 2% 98 158.6 sucrose 3 LTO/C 2% 98 159.0 starch

TABLE-US-00005 TABLE 5 Test results for the materials of Comparison example 4 LTO Specific Average Carbon LTO crystallite surface Pore pore Specific content content size area volume size capacity Example Sample [%] [%] [nm] [m.sup.2/g] [cm.sup.3/g] [nm] [mAh/g] 1 LTO/C 50% 25.3 50 (800 C.) 2 LTO/C 50% 11.1 50 5 (850 C.)

LIST OF LITERATURE CITED IN THE DESCRIPTION

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