PROCESS FOR MAKING A LITHIATED TRANSITION METAL OXIDE

Abstract

Process for manufacturing a lithiated transition metal oxide, said process comprising the steps of (a) mixing at least one lithium salt and a precursor selected from transition metal oxides, transition metal oxyhydroxides, transition metal hydroxides, and transition metal carbonates, (b) pre-calcining the mixture obtained in step (a) at a temperature in the range of from 300 to 700° C., and (c) calcining the pre-calcined mixture according to step (b) in a multi-stage fluidized bed reactor at a temperature in the range of from 550° C. to 950° C., wherein the temperatures in step (b) and (c) are selected in a way that step (c) is being performed at a temperature higher than that of step (b).

Claims

1. A process for manufacturing a lithiated transition metal oxide, the process comprising: (a) mixing at least one lithium salt and a precursor selected from the group consisting of transition metal oxides, transition metal oxyhydroxides, transition metal hydroxides, and transition metal carbonates; (b) pre-calcining the mixture obtained in step (a) at a temperature in the range of from 300 to 700° C.; and (c) calcining the pre-calcined mixture according to step (b) in a multi-stage fluidized bed reactor at a temperature in the range of from 550° C. to 950° C., wherein the temperatures in step (b) and (c) are selected such that step (c) is performed at a temperature higher than that of step (b).

2. The process according to claim 1, wherein step (b) is performed in a rotary kiln, rotary hearth kiln, pendulum kiln, roller hearth kiln, tunnel kiln, packed bed reactor, fluidized bed reactor, or in a separate stage of a fluidized bed.

3. The process according to claim 1, wherein step (b) is performed in a separate stage of a fluidized bed wherein said separate stage has the same as or a larger hold-up than the other stages.

4. The process according to claim 1, wherein the precursor has an average particle diameter (D50) in the range of from 3 to 20 μm.

5. The process according to claim 1, wherein said precursor contains the cations of at least two transition metals selected from nickel, cobalt, and manganese.

6. The process according to claim 1, wherein the heat in step (c) is at least partially transferred by thermal radiation.

7. The process according to claim 1, wherein step (c) is performed in a multi-stage fluidized bed with in the range of from 3 to 20 stages.

8. The process according to claim 1, wherein different stages of the reactor wherein step (c) is performed are separated from each other through physical provisions.

9. The process according to claim 8, wherein the different stages of the reactor wherein step (c) is performed are connected with each other through standpipes.

10. The process according to claim 1, wherein the apparatus wherein step (c) is being performed has a surface made from ceramic material.

11. The process according to claim 1, wherein the lithiated transition metal oxide is selected from the group consisting of lithiated spinels, layered oxides, and lithium nickel-cobalt-aluminum oxides.

12. The process according to claim 1, wherein the iron content of the lithiated transition metal oxide is in the range of from 1 to 75 ppm.

13. The process according to claim 1, wherein the at least one lithium salt is selected from the group consisting of lithium hydroxide, lithium oxide, and lithium carbonate.

14. The process according to claim 1, wherein the precursor is selected from the group consisting of mixed transition metal oxides, mixed transition metal oxyhydroxides, mixed transition metal hydroxides, and mixed transition metal carbonates of at least two transition metals.

15. The process according to claim 1, wherein step (c) is carried out in the presence of a chemically inert particulate material.

Description

EXPLANATIONS OF TERMS

[0081] RS: reactor system
Nm.sup.3: norm cubic meter, thus, at ambient temperature and atmospheric pressure Settled bed height: entire height of the settled bed as if transferred into an empty cylinder with the same cross-section
Ratio fluidized bed height/settled bed height
Height between bed and stage: distance between upper level of respective stage of fluidized bed and a perforated plate of the next stage
I. Synthesis of a Lithium Transition Metal Oxide with a Layered Structure

TABLE-US-00001 TABLE 1 Parameters of tubular reactors for carrying out the examples RS.1 RS.2 RS.3 RS.4 RS.5 cross-sectional area [m.sup.2] 0.196 0.196 0.283 0.442 0.00811 reactor total height [m] 17.0 17.0 11.8 7.5 3 ratio height/diameter per stage 1.0 1.5 0.83 0.67 29.5 settled bed height per stage [m] 0.5 0.75 0.5 0.3 0.38 expansion factor of fluidized bed 1.1 1.1 1.1 1.1 1.1 height fluidized bed height per stage [m] 0.55 0.825 0.55 0.33 0.42 Number of stages 34 23 24 26 1 Number of stages for step (c), ±1 17 11 12 13 1 Solids residence time per stage 14.1 20.9 20.0 18.5 240 [min] Volumetric gas flow [Nm.sup.3/h] 50 50 75 75 3.35 superficial gas flow at 25° C. [cm/s] 7 7 7 5 11.5 superficial gas flow at 925° C. 28 28 30 19 13.4 [cm/s] mass flow of gas [kg/h] 58.4 58.4 87.6 87.6 96 height between bed and stage [m] 0.2 0.2 0.2 0.2 n/a Total height of reactor system [m] 25.3 23.4 17.8 13.6 5 n/a: not applicable.

[0082] Step (a.1):

[0083] In such a reactor, a precursor of formula Ni.sub.0.33Co.sub.0.33Mn.sub.0.33(OH).sub.2, average particle diameter 12 μm, is mixed with 1.12 equivalents of Li.sub.2CO.sub.3, average particle diameter 5.5 μm, equivalents of Li referring to total transition metal content of said precursor.

[0084] Step (b.1): the mixture obtained in step (a.1) is pre-calcined at a temperature of 675° C.

[0085] Then, step (c.1) is begun in a fluidized bed reactor with distributor plates and standpipes made from high density alumina and alumina shielded reactor inner walls. The gas inlet temperature is 25° C., the maximum temperature of the gas is 925° C. The heat is reached by electrical heating of the walls. The required heat flow to heat up the solids from 25° C. to 925° C. is approximately 166.7 kW. In this example, the required heat flow is only partially provided by external heat introduction and the main amount of the heat is transferred by the gas to the particles (heat recovery). The respective step (c.1) to (c.4) is performed at 50% of the stages, the other stages serve for heating of the particles of the precursor to the desired temperature or cooling them down to ambient temperature.

[0086] A cathode active material of the formula Li.sub.1.06(Ni.sub.0.33Co.sub.0.33Mn.sub.0.33).sub.0.94O.sub.2 was obtained. The iron content was less than 75 ppm.

II. Synthesis of a Lithiated Ni—Co—Al Oxide

[0087] (a.II) In reactor system RS.1, a mixture of LiOH, Al.sub.2(OH).sub.3, and a precursor of formula Ni.sub.0.84Co.sub.0.16(OH).sub.2 are mixed in such way that the final nickel cobalt aluminum cathode material has a lithium to metal ratio of 1.02, with metals in this context being nickel, cobalt, and aluminum. The amount of aluminum hydroxide is defined by the ratio of atoms in the final lithiated nickel cobalt aluminum layered oxide, which is Ni.sub.0.81Co.sub.0.15Al.sub.0.04.

[0088] (b.II) The mixture obtained in step (a.II) is pre-calcined at a temperature of 400° C. for 4 hours followed by pre-calcination at 675° C. for 6 hours. Both pre-calcination dwells are conducted in oxygen atmosphere.

[0089] (c.II) The system for calcination is the same as described in (c.1). Calcination is conducted in oxygen atmosphere. The material temperature in the highest temperature zone is 780° C. The residence time of the material in the highest temperature zone is 6 hours.

[0090] A cathode active material of the formula Li.sub.1.01(Ni.sub.0.81Co.sub.0.15Al.sub.0.04).sub.0.99O.sub.2 is obtained. The iron content is less than 75 ppm.

III. Synthesis of a Lithiated Spinel

[0091] (a.III) In reactor system RS.1, Li.sub.2CO.sub.3 is mixed with spinel precursor of formula Ni.sub.0.5Mn.sub.1.5(OH).sub.4 in such way that the lithium to transition metal ratio is 1.01.

[0092] (b.III) The obtained mixture is pre-calcined at 375° C. for 3 hours and at 650° C. for 6 hours, both in an atmosphere of air.

[0093] (c.III) The calcination of the material is conducted in the same system as described in (c.1). The calcination is run in air. The calcination is run in such way that the material is treated at 820° C. for 6 hours with 820° C. being the highest temperature the material reaches in the course of the calcination.

[0094] A cathode active material of the formula Li.sub.1.01(Ni.sub.0.5Mn.sub.1.5).sub.0.99O.sub.2 is obtained. The iron content is less than 75 ppm.

IV. Synthesis of a Lithium Transition Metal Oxide with a Layered Structure in the Presence of a Chemically Inert Particulate Material

[0095] Aluminum Oxide White from AGSCO Corporation was used as chemically inert particulate material. The crystal form was α-alumina, the chemical nature was amphoteric, the particle density was 3.95 g/cm.sup.3, the loose back bulk density was 1.61-1.87 g/cm.sup.3, the Mohs hardness was 9, the melting point 2000° C. The particle size distribution was measured with a Horiba Particle Size Distribution Analyzer LA-950 V2. The average particle diameter of the chemically inert particulate material was 52.3 μm.

[0096] Steps (a.1) and (a.2) were repeated as above. Before charging the reactor system RS.5, however, an amount of the above aluminum oxide white was added to the precalcined mixture obtained from step (b.1) so that the weight ratio of aluminum oxide white to precursor was 7:3. The precalcined mixture was filled into a glass vessel cold flow fluidized bed system first, the alumina then was also filled into the same vessel. Mixing was performed by fluidizing the vessel load for one minute. Quality of the mixture was determined visually. The mixture so obtained was then filled into reactor system RS.5. The fluidization was performed in accordance with Table 1 as a batch operation, maintaining a bed temperature of 925° C. for 2 hours.

[0097] A cathode active material of the formula Li.sub.1.06(Ni.sub.0.33Co.sub.0.33Mn.sub.0.33).sub.0.94O.sub.2 was obtained. The iron content was less than 75 ppm.