Lithium-mixed oxide particles encapsulated in aluminum oxide and titanium dioxide, and method for using same

Abstract

Process for producing coated mixed lithium oxide particles, in which mixed lithium oxide particles and a mixture comprising aluminium oxide and titanium dioxide are subjected to dry mixing by means of a mixing unit having a specific power of 0.1-1 kW per kg of mixed lithium oxide particles and mixture used, in total, under shearing conditions. Coated mixed lithium oxide particles comprising a mixture of aluminium oxide and titanium dioxide as coating material, wherein the aluminium oxide and the titanium dioxide are in the form of aggregated primary particles and the weight ratio of aluminium oxide to titanium dioxide is 10:90-90:10. Battery cell comprising the coated mixed lithium oxide particles.

Claims

1. A process for producing coated mixed lithium oxide particles, comprising dry mixing: a) mixed lithium oxide particles, and b) a mixture comprising aluminium oxide and titanium dioxide; using a mixing unit having a specific power of 0.1-1 kW per kg of mixed lithium oxide particles and mixture used, in total, under shearing conditions; and wherein there is not a thermal treatment after mixing.

2. The process of claim 1, wherein the aluminium oxide and/or the titanium dioxide is in the form of aggregated primary particles.

3. The process of claim 2, wherein the aggregated primary particles are formed by pyrogenic means.

4. The process of claim 3, wherein: a) the weight ratio of aluminium oxide to titanium dioxide is 10:90-90:10; b) aluminium oxide particles having a BET surface area of at least 115 m2/g are used; c) the proportion of (aluminium oxide+titanium dioxide) is 0.05%-5% by weight, based on the sum total of mixed lithium oxide particles and (aluminium oxide+titanium dioxide).

5. The process of claim 4, wherein the mixed lithium oxide particles are selected from the group consisting of lithium-cobalt oxides, lithium-nickel-manganese-cobalt oxides, lithium-nickel-cobalt-aluminium oxides, lithium-manganese oxides, lithium-nickel-manganese oxides, or a mixture of these.

6. The process of claim 1, wherein the weight ratio of aluminium oxide to titanium dioxide is 10:90-90:10.

7. The process of claim 6, wherein the aluminium oxide particles and titanium dioxide particles are each in the form of aggregated primary particles.

8. The process of claim 7, wherein the mixed lithium oxide particles are selected from the group consisting of lithium-cobalt oxides, lithium-nickel-manganese-cobalt oxides, lithium-nickel-cobalt-aluminium oxides, lithium-manganese oxides, lithium-nickel-manganese oxides, or a mixture of these.

9. The process of claim 8, wherein the proportion of (aluminium oxide+titanium dioxide) is 0.05%-5% by weight, based on the sum total of mixed lithium oxide particles and (aluminium oxide+titanium dioxide).

10. The process of claim 1, wherein aluminium oxide particles having a BET surface area of at least 115 m.sup.2/g are used.

11. The process of claim 1, wherein the aluminium oxide particles are selected from the group consisting of γ-, θ-, δ-aluminium oxide and mixtures of these.

12. The process of claim 1, wherein titanium dioxide particles having a BET surface area of at least 40 m.sup.2/g are used.

13. The process of claim 1, wherein the BET surface area of the aluminium oxide particles used is greater than that of the titanium dioxide particles used.

14. The process of claim 1, wherein the aluminium oxide particles and titanium dioxide particles are each in the form of aggregated primary particles.

15. The process of claim 1, wherein the mixed lithium oxide particles are selected from the group consisting of lithium-cobalt oxides, lithium-nickel-manganese-cobalt oxides, lithium-nickel-cobalt-aluminium oxides, lithium-manganese oxides, lithium-nickel-manganese oxides, or a mixture of these.

16. The process of claim 1, wherein the proportion of (aluminium oxide+titanium dioxide) is 0.05%-5% by weight, based on the sum total of mixed lithium oxide particles and (aluminium oxide+titanium dioxide).

17. The process of claim 16, wherein the aluminium oxide particles are selected from the group consisting of γ-, θ-, δ-aluminium oxide and mixtures of these.

18. The process of claim 17, wherein the aluminium oxide particles and titanium dioxide particles are each in the form of aggregated primary particles.

Description

(1) This compares

(2) (A) LCO powder coated by the process according to the invention with a 50:50 mixture of AEROXIDE® Alu 130 and AEROXIDE® TiO2 P25 with

(3) (B) LCO powder coated with AEROXIDE® Alu 130 only and

(4) (C) non-coated LCO powder.

(5) The axes show: x axis=number of cycles; y axis=normalized cell capacity in %;

(6) Charging switch-off voltage=4.4 V; temperature=45° C.

(7) (A) shows a higher cell capacity over the entire cycling range.

(8) It is known that the cycling of cells gives rise to breakdown products that can increase the internal resistance of the cell and also the temperature thereof. The DCIR value should therefore be very low and relatively stable over hundreds of cycles. In the case of uncoated LCO and Al.sub.2O.sub.3-coated LCO, it seems that a layer which is always less permeable to the current grows around the active cathode material, which is manifested in a higher DCIR.

(9) The table shows that this effect is much less marked in the case of the mixed lithium oxide particles that have been coated in accordance with the invention.

(10) TABLE-US-00001 TABLE Internal resistance (DCIR*) in ohm .Math. cm.sup.2 of the electrochemical cell with/without coating Sample 3rd cycle 450th cycle LCO LC412 15.4 96.6 AEROXIDE ® Alu 130 + LCO LC412 17.7 92.6 AEROXIDE ® Alu 130 + TiO2 P25 + LCO 8.0 18.7 LC412 *direct current internal resistance; pouch full-cell tests; voltage range: 3.0-4.4 V; temperature: 45° C.; forming at 0.02 C/0.3 C; cycling at 1 C/1 C; electrode size: 25 cm.sup.2