METHOD FOR PRODUCING A CATHODE MATERIAL AND SPECIAL CATHODE MATERIAL

Abstract

A pulverulent cathode material contains at least one mixed oxide containing the metal components Li, at least one further metal component selected from the group consisting of Mn, Ni and Co. The pulverulent cathode material is produced by a process in which an ammonia-containing aerosol containing metal compound of the metal components is converted in a high-temperature zone of a reaction space and then the solids are removed.

Claims

1. A process for producing a pulverulent cathode material, said cathode material comprising at least one mixed oxide containing metal component Li, at least one further metal component selected from the group consisting of Mn, Ni and Co, said process comprising: converting an ammonia-containing aerosol containing metal compound of the metal component in a high-temperature zone of a reaction space and then removing the solids.

2. The process for producing the pulverulent cathode material according to claim 1, wherein the aerosol is obtained by atomizing a solution containing the metal compounds by an atomization gas.

3. The process according to claim 1, wherein the concentration of ammonia is 0.5-5.0 kg/kg of the sum total of the metals used, in kg/kg.

4. The process according to claim 1, wherein the atomization is effected by means of a one-phase or multiphase nozzle and the mean droplet diameter of the aerosol is not more than 100 μm.

5. The process according to claim 1, wherein the high-temperature zone into which the aerosol is introduced is a flame which is formed by the reaction of an oxygen-containing gas and a combustion gas.

6. The process according to claim 5, wherein the following applies to the ratio of mean velocity of the mixture to mean velocity of the flame: 2≦V.sub.aerosol/V.sub.flame≦10.

7. The process according to claim 1, wherein the solution contains at least one dopant compound containing a metal selected from the group consisting of Ag, Al, B, Ca, Cr, Cu, Fe, Ga, Ge, In, K, Mg, Mo, Na, Nb, Si, Sn, Ta, Ti, Tl, V and Zr.

8. The process according to claim 1, wherein at least one metal compound is a nitrate.

9. The process according to claim 1, wherein the solids removed are subjected to thermal treatment at temperatures of 850 to 1000° C. over a period of 2 to 36 h.

10. A pulverulent cathode material in the form of aggregated primary particles, comprising a mixed oxide powder having a composition corresponding to Li.sub.1+x(Ni.sub.aCo.sub.bMn.sub.c)D.sub.dO.sub.2, and H and N as non-metal components, with a proportion of H of 0.01%-0.1% by weight and a proportion of N of 0.002%-0.05% by weight, based in each case on the pulverulent cathode material, where D=Ag, Al, B, Ca, Cr, Cu, Fe, Ga, Ge, In, K, Mg, Mo, Na, Nb, Si, Sn, Ta, Ti, Tl, V and Zr, and 0<x≦0.2; 0<a≦1; 0≦b≦1; 0≦c≦1, 0≦d≦0.2.

11. The pulverulent cathode material in the form of aggregated primary particles according to claim 10, wherein 0<x≦0.2, 0.1≦a≦0.2; 0.05≦b≦0.2; 0.5<c≦0.6 and d=0.

12. The pulverulent cathode material in the form of aggregated primary particles according to claim 10, wherein 0<x≦0.2, 0<a≦1, b=0, 0.5<c≦0.6 and 0.05<d≦0.1.

13. The pulverulent cathode material in the form of aggregated primary particles according to claim 11, wherein the mean relative concentration of the elements Ni, Mn and Co, which is determined by means of TEM-EDX from 18 randomly selected regions each comprising a volume of about 500 nm.sup.3 of the cathode material, does not deviate by more than 5% from the concentration of the pulverulent cathode material determined by means of ICP-OES, inductively coupled plasma optical emission spectrometry.

14. The pulverulent cathode material in the form of aggregated primary particles according to claim 11, wherein the standard deviation in the relative concentration of the elements Ni, Mn and Co, which is determined by TEM-EDX from 18 randomly selected regions each comprising a volume of about 500 nm.sup.3 of the cathode material, is not more than 5% per element.

15. A lithium ion battery batteries, comprising: the pulverulent cathode material according to claim 10.

Description

[0022] The solvent may preferably be selected from the group consisting of water, C.sub.5-C.sub.20-alkanes, C.sub.1-C.sub.15-alkanecarboxylic acids and/or C.sub.1-C.sub.15-alkanols. More preferably, it is possible to use water or a mixture of water and an organic solvent. Organic solvents used, or constituents used in mixtures of organic solvents, may preferably be alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol or tert-butanol, diols such as ethanediol, pentanediol, 2-methylpentane-2,4-diol, C.sub.1-C.sub.12-carboxylic acids, for example acetic acid, propionic acid, butanoic acid, hexanoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, octanoic acid, 2-ethylhexanoic acid, valeric acid, capric acid, lauric acid. It is additionally possible to use benzene, toluene, naphtha and/or benzine. Preference is given to using an aqueous solvent.

[0023] FIG. 1 shows a schematic of a possible arrangement for introduction of the feedstocks into the reaction space, where: 1=solution containing metal compounds, 2=atomizing gas, 3=ammonia, 4=air, 5=combustion gas, A=reaction chamber wall.

[0024] A further embodiment of the invention envisages that the solids removed are subjected to thermal treatment at temperatures of 850 to 1000° C. over a period of 2 to 36 h. The treatment can be effected in the presence of air or oxygen-enriched air, corresponding to an oxygen content of 21%-40% by volume. Treatment in oxygen-enriched air gives the best results.

[0025] The invention further provides a pulverulent cathode material in the form of aggregated primary particles, comprising a mixed oxide powder having a composition corresponding to Li.sub.1+x(Ni.sub.aCo.sub.bMn.sub.c)D.sub.dO.sub.2, and H and N as non-metal components, with

a proportion of H of 0.01%-0.1% by weight and
a proportion of N of 0.002%-0.05% by weight, based in each case on the pulverulent cathode material, where D=Ag, Al, B, Ca, Cr, Cu, Fe, Ga, Ge, In, K, Mg, Mo, Na, Nb, Si, Sn, Ta, Ti, Tl, V and Zr, and 0<x≦0.2; 0<a≦1; 0≦b≦1; 0≦c≦1, 0≦d≦0.2.

[0026] Preferably, 0<x≦0.2, 0.1≦a≦0.2; 0.05≦b≦0.2; 0.5<c≦0.6 and d=0 or 0<x≦0.2; 0<a≦1; b=0; 0.5<c≦0.6 and 0.05<d≦0.1.

[0027] Primary particles are the smallest particles that are not divisible any further and are detectable, for example, by means of transmission electron microscopy (TEM). The mean primary particle diameter can be determined, for example, by counting the particles in TEM images. Several primary particles join together firmly at their contact sites to form aggregates. The aggregate dimensions can be determined, for example, by laser diffractometry. The cathode material according to the invention, after an optional heat treatment, has a mean particle size of 1 to 10 μm.

[0028] In a specific embodiment, it is a feature of the pulverulent cathode material according to the invention that the mean relative concentration of the elements Ni, Mn and Co, which is determined by means of TEM-EDX from 18 randomly selected regions each comprising a volume of about 500 nm.sup.3 of the cathode material, does not deviate by more than 5% from the concentration of the pulverulent cathode material determined by means of ICP-OES, inductively coupled plasma optical emission spectrometry.

[0029] In a specific embodiment, it is a feature of the pulverulent cathode material according to the invention that the standard deviation in the relative concentration of the elements Ni, Mn and Co, which is determined by means of TEM-EDX from 18 randomly selected regions each comprising a volume of about 500 nm.sup.3 of the cathode material, is not more than 5% per element.

[0030] The invention further provides for the use of the pulverulent cathode material according to the invention as a constituent of lithium ion batteries.

EXAMPLES

[0031] Analysis

[0032] TEM-EDX: The samples are each analysed at 18 different, representative sites by means of the EDX analysis. The volume analysed is about 500 nm.sup.3 per measurement point. The analyses were conducted with a Jeol 2010F transmission electron microscope at acceleration voltage 200 kV and a Noran EDX analysis with the NSS 3.1 evaluation software.

[0033] ICP-OES: The metal concentrations were determined by means of ICP-OES. The samples were analysed with the PerkinElmer Optima ICP-OES system. The relative uncertainty in the results for the metals is 0.5%-2%.

[0034] H, N: The hydrogen and nitrogen content is determined by means of the LECO TCH600 elemental analyser. The uncertainty in the results is 0.8%-1.0%.

[0035] BET: The BET surface area is determined to DIN ISO 9277.

[0036] Electrochemical characterization: The cathode materials are incorporated into a customary standard slurry. The proportion by mass of the cathode material in the slurry is 32.7% by weight. Subsequently, the electrochemical cells produced are cycled between 2.0 and 4.6 V at 25° C. The charging and discharging currents are fixed at 25 mAh/g of cathode material.

[0037] Solutions used: For Examples 1 to 6, a solution comprising the salts specified in Table 1 is prepared in each case with water as solvent. An aerosol is produced from the solution and atomizer air by means of a nozzle and is atomized into a reaction space. The aerosol is reacted in a hydrogen/air flame which burns here. After cooling, the cathode material is separated from gaseous substances at a filter. The solid product is heated to a temperature of 875 to 1000° C. in a rotary tube oven within 3 to 10 hours. Subsequently, it is kept at this temperature over a period of 4 to 10 hours and subsequently cooled to room temperature over a period of about 12 hours.

[0038] Table 1 gives all the relevant parameters for preparation of the cathode material and important physical properties of the powders obtained, along with their electrochemical properties.

[0039] Table 2 shows the homogeneous distribution of a comparative material which has been produced without ammonia, with a cathode material produced by the process according to the invention.

TABLE-US-00001 TABLE 1 Preparation of Li.sub.1+x(Ni.sub.aCo.sub.bMn.sub.c)D.sub.dO.sub.2 Example Comp. According to invention 1 2 3 4 5 6 x 0.2 0.2 0.2 0.2 0.2 0.2 a 0.13 0.13 0.16 0.13 0.16 0.16 b 0.13 0.13 0.08 0.13 0.08 0 c 0.54 0.54 0.56 0.54 0.56 0.56 D — — — — — Al d — — — — — 0.08 Flame spray pyrolysis Solution Lithium nitrate % by wt. 14.86 14.86 14.86 14.86 14.86 15.71 Nickel (II) nitrate % by wt. 4.09 4.09 4.09 4.09 4.09 5.54 Manganese (II) nitrate % by wt. 16.64 16.64 16.64 16.64 16.64 19.02 Cobalt (II) nitrate % by wt. 4.10 4.10 4.10 4.10 4.10 0 Aluminium nitrate % by wt. 0 0 0 0 0 3.23 Total metal % by wt. 9.25 9.25 9.25 9.25 9.25 9.56 Throughput kg/h 7 8 9 6 5 8 Atomization air m.sup.3 13 14 17 12 13 17 (STP)/h Ammonia kg/h — 1.14 1.14 1.14 1.14 0.76 Ammonia/metal kg/kg 0 1.54 1.37 2.05 2.46 0.99 Hydrogen m.sup.3 15 15 10 13 15 11 (STP)/h Air m.sup.3 75 75 80 85 75 75 (STP)/h Lambda 2.10 2.10 3.36 2.75 2.10 2.86 V.sub.aerosol Nm/s 134 134 119 93 87 87 V.sub.flame Nm/s 14.6 15.7 15.7 16.2 15.7 15.0 V.sub.aerosol/V.sub.flame 9.18 8.54 7.58 5.74 5.54 4.27 T.sub.flame.sup.a) ° C. 783 808 511 947 1086 680 BET.sup.b).sub.FSP m.sup.2/g 39 13 31 38 34 27 Heat treatment T.sub.furnace ° C. 930 960 930 875 900 960 t.sub.heating h 6 6 6 6 6 6 BET.sub.temp m.sup.2/g 6.76 3.41 7.26 8.75 8.33 4.10 H.sup.b) % by wt. 0.016 0.035 0.059 0.088 0.077 0.058 N.sup.b) % by wt. 0.010 0.030 0.009 0.027 0.004 0.002 C/10 (2nd cycle) mAh/g 202 246 240 253 241 173 C/10 (60th cycle) mAh/g 172 222 224 233 219 177 C10 % 85.1 90.2 93.3 92.1 90.9 102.3 (60th cyc./2nd cyc.) C3 mAh/g 151 207 206 194 204 130 1C mAh/g 111 142 161 143 157 103 1st eff. % 60 74 72 79.8 73 64 Fading 1C mAhg.sup.−1/Z 0.136 0.096 0.078 0.037 0.082 0.150 .sup.a)flame temperature; measured 10 cm below the feed point of hydrogen and air into the reaction space; .sup.b)after heat treatment

TABLE-US-00002 TABLE 2 Homogeneity of the cathode material (at % normalized to 100) Example 1 (comparison) 2 (according to invention) Image Mn Co Ni Mn Co Ni 1 66.7 16.7 16.7 68.6 17.1 15.3 2 64.3 17.9 17.9 65.6 15.6 16.8 3 70.4 14.8 14.8 68.0 16.0 16.0 4 68.0 16.0 16.0 70.4 14.8 15.8 5 70.4 14.8 14.8 65.7 20.0 15.3 6 71.0 16.1 12.9 64.9 18.9 16.2 7 72.0 16.0 12.0 66.7 17.9 15.4 8 75.0 12.5 12.5 66.7 18.5 14.8 9 35.0 30.0 35.0 67.9 17.9 15.3 10 52.2 18.9 18.9 69.2 15.4 15.4 11 44.2 27.9 27.9 66.7 18.5 15.8 12 58.8 20.6 20.6 70.4 14.8 14.8 13 71.0 16.1 12.9 63.0 18.5 18.5 14 66.7 16.7 16.7 66.7 16.7 16.7 15 54.1 14.8 11.1 70.0 16.7 16.3 16 65.6 21.9 12.5 68.0 16.0 16.0 17 65.4 17.3 17.3 69.0 17.2 15.8 18 69.2 15.4 15.4 71.9 15.6 15.5 σ.sub.(EDX) 10.0 4.3 5.7 2.1 1.4 0.8 m.sub.avg(EDX) 63.3 18.0 17.0 67.7 17.0 15.9 m.sub.avg(ICP) 66.8 17.1 16.1 66.8 17.1 16.1 m.sub.avg(EDX)/ 94.8 105.4 105.6 101.4 99.4 98.6 m.sub.avg(ICP)