Lithium cobalt aluminum oxide positive electrode material and preparation method thereof, and lithium ion battery

Abstract

The present invention relates to the field of lithium-ion batteries and discloses a lithium cobalt aluminate positive electrode material, a preparation method thereof, and a lithium-ion battery. The lithium cobalt aluminate positive electrode material is a single-crystal particle; the positive electrode material particles contain a single or multiple pore structures. The positive electrode material having such a structure has a high particle structure stability. When used in lithium-ion batteries, it has a significantly higher charge and discharge voltage window, a higher capacity retention rate (cycle life), and improved safety.

Claims

1. A lithium cobalt aluminum oxide positive electrode material, characterized in that: The lithium cobalt aluminate positive electrode material is a single crystal positive electrode material particle; the positive electrode material particle contains a single or multiple pore structures; The volume of the positive electrode material particles is V0, and the total volume of the pore structure in the particles is V1, wherein 0.059%≤V1 / V0×100%≤1.631%; The ratio of the major axis to the minor axis of the pores in the pore structure is 1-1.5:1; The average diameter of the positive electrode material particles is Dc, and the average diameter of the holes in the hole structure is Dh, wherein 1.58% <Dh / Dc×100%≤15%。 2. The lithium cobalt aluminate positive electrode material according to claim 1, wherein The ratio of the major axis to the minor axis of the holes in the hole structure is 1-1.2:

1.

3. The lithium cobalt aluminate positive electrode material according to claim 1 or 2, wherein 0μm <D h ≤5μm.

4. The lithium cobalt aluminate positive electrode material according to claim 3, wherein 0.1μm≤D h ≤3μm。 5. The lithium cobalt aluminate positive electrode material according to claim 1 or 2, wherein The cross-sectional area of ​​the positive electrode material particle is S0, and the total area of ​​the pore structure in the particle is S1, wherein 0% <S1 / S0×100%≤30%。 6. The lithium cobalt aluminate positive electrode material according to claim 5, wherein The cross-sectional area of ​​the positive electrode material particles is S0, and the total area of ​​the pore structure in the particles is S1, wherein 0.1%≤S1 / S0×100%≤15%.

7. The lithium cobalt aluminate positive electrode material according to claim 1 or 2, wherein: The true density of the lithium cobalt aluminate positive electrode material is ≤5g / cm 3 .

8. The lithium cobalt aluminate positive electrode material according to claim 7, wherein The true density of the lithium cobalt aluminate positive electrode material is ≤4.98 g / cm 3 .

9. The lithium cobalt aluminate positive electrode material according to claim 1 or 2, wherein: The powder compaction density of the lithium cobalt aluminate positive electrode material is ≥4g / cm 3 .

10. The lithium cobalt aluminate positive electrode material according to claim 9, wherein: The powder compaction density of the lithium cobalt aluminate positive electrode material is ≥4.1 g / cm 3 .

11. The lithium cobalt aluminate positive electrode material according to claim 1 or 2, wherein: The positive electrode material has a composition shown in Formula I: Li n Co a Al b M’ 1-a-b O2 type I Among them, 0.9≤n≤1.05, 0.9≤a≤0.995, 0.005≤b≤0.1, 0≤1-ab≤0.02; M' is at least one element selected from the group consisting of Na, B, W, Mo, V, Si, Hf, Ta, Al, Y, Sr, Ba, Er, Mg, Ti, Zr, La, Ce, P, and Nb.

12. The lithium cobalt aluminate positive electrode material according to claim 11, wherein 0.95≤n≤1.03, 0.95≤a≤0.99, 0.01≤b≤0.05, 0.001≤1-ab≤0.

01.

13. The lithium cobalt aluminate positive electrode material according to claim 11, wherein M' is at least one element selected from the group consisting of Na, B, Al, Mg, Sr, Ba, Zr, La, and Y.

14. A method for preparing the lithium cobalt aluminate positive electrode material according to any one of claims 1 to 13, characterized in that: The preparation method comprises the following steps: S1, mixing a lithium cobalt aluminate positive electrode material precursor, a lithium source and an additive 1 to obtain a mixture I; S2. calcining, cooling, crushing, and screening the mixture I to obtain a lithium cobalt aluminate positive electrode material in process; S3, mixing the lithium cobalt aluminate positive electrode material process product, additive 2 and additive 3 to obtain a mixture II; S4, calcining, cooling, screening, and demagnetizing the mixture II to obtain the lithium cobalt aluminate positive electrode material; The additive 1 is a compound containing an M' element; Wherein, the amounts of the lithium cobalt aluminate positive electrode material precursor, the lithium source and the additive 1 are such that 0.9≤n(Li) / [n(Co)+n(Al)+n(M')]≤1.05; 0≤n(M') / [n(Co)+n(Al)+n(M')]≤0.02; The roasting includes a first roasting stage and a second roasting stage; the oxygen concentration vol1 in the first roasting stage and the oxygen concentration vol2 in the second roasting stage are controlled to satisfy: vol2<vol1; Wherein, T1 is the first roasting temperature, 600°C≤T1≤900°C, t1 is the first roasting time, 2h≤t1≤6h; T2 is the second roasting temperature, 900°C≤T2≤1100°C, t2 is the second roasting time, 6h≤t2≤15h.

15. The preparation method according to claim 14, wherein The oxygen concentration vol1 in the first calcination stage and the oxygen concentration vol2 in the second calcination stage satisfy: vol1-vol2 is greater than 0 vol% and less than or equal to 80 vol%, and vol1≥21 vol%.

16. The preparation method according to claim 15, wherein The oxygen concentration vol1 in the first calcination stage and the oxygen concentration vol2 in the second calcination stage satisfy: vol1-vol2 is 20-60 vol%, and vol1≥40 vol%.

17. The preparation method according to claim 14, wherein The roasting is carried out according to the following steps: (a) First calcination stage: in an oxygen-containing atmosphere with an oxygen concentration of vol1, the temperature is raised from 0°C to T1°C and maintained in the temperature range of T1-10°C to T1+10°C for t1 hour; (b) Second calcination stage: in an oxygen-containing atmosphere with an oxygen concentration of vol2, the temperature is raised from T1°C to T2°C and kept in the range of T2-10°C to T2+10°C for t2 hours.

18. The preparation method according to claim 14, wherein The additive 2 is a compound containing an M' element; M' is at least one element selected from the group consisting of Na, B, W, Mo, V, Si, Hf, Ta, Al, Y, Sr, Ba, Er, Mg, Ti, Zr, La, Ce, P, and Nb.

19. The preparation method according to claim 18, wherein The amount of the lithium cobalt aluminate positive electrode material product and the additive 2 is such that 0≤n(M') / [n(Co)+n(Al)+n(M')]≤0.

02.

20. The preparation method according to claim 14, wherein The additive 3 is a compound containing Co element.

21. The preparation method according to claim 20, wherein The amounts of the lithium cobalt aluminate positive electrode material product and the additive 3 are such that the ratio of the molar amount of the Co element in the lithium cobalt aluminate positive electrode material product to the molar amount of the Co element in the additive 3 is 1:0.01-0.

1.

22. The preparation method according to claim 14, wherein The calcination conditions include: a calcination temperature of 800-1000° C. and a calcination time of 4-10 hours.

23. The preparation method according to claim 14, wherein The lithium cobalt aluminum oxide positive electrode material precursor is prepared according to the following steps: (1) Cobalt salt and aluminum salt are prepared into a mixed salt solution; precipitant and complexing agent are prepared into precipitant solution and complexing agent solution respectively; (2) introducing the mixed salt solution, precipitant solution and complexing agent solution into a reaction kettle simultaneously and separately, reacting and aging to obtain a solid-liquid mixture; (3) The solid-liquid mixture is filtered to obtain a filter cake, and the filter cake is washed, dried, and subjected to low-temperature heat treatment to obtain the lithium cobalt aluminate positive electrode material precursor.

24. The preparation method according to claim 23, wherein The cobalt salt and the aluminum salt are configured into a mixed salt solution according to a molar ratio of n(Co):n(Al)=(0.8-0.985):(0.005-0.1).

25. The preparation method according to claim 23, wherein The reaction conditions include: reaction temperature of 40-70° C. and pH value controlled in the range of 7-9.

26. The preparation method according to claim 23, wherein The aging time is 2-12 hours.

27. The preparation method according to claim 23, wherein The low-temperature heat treatment conditions include: treating at a temperature of 500-900° C. for 1-5 hours in the presence of air and / or oxygen.

28. A lithium ion battery, characterized in that: The lithium-ion battery comprises the lithium cobalt aluminate positive electrode material according to any one of claims 1 to 13.

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