Sodium-ion battery, positive pole piece for sodium-ion battery, positive active material, battery module, battery pack and device

By doping the low-priced Li in the layered transition metal oxide positive electrode material and controlling the Rct/Rf ratio, the problem of insufficient performance of the positive electrode material of sodium ion battery is solved, and higher cyclic stability and electrochemical performance are achieved.

CN120109147APending Publication Date: 2025-06-06CONTEMPORARY AMPEREX TECHNOLOGY CO LTD
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Patent Information

Application Number
CN202510243903.0
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2019-10-18
Publication Date
2025-06-06

AI Technical Summary

Technical Problem

The performance of the positive electrode material of existing sodium ion batteries is insufficient, which affects the electrochemical performance and cycling stability of the battery.

Method used

Transition metal oxides with a layered structure are used as the positive electrode active material, and inactive transition metal Li in a low-valent state are doped therein, and the ratio of Rct to Rf is controlled to be within the range of 1.0 < Rct/Rf < 20.0 to improve the cyclic stability and electrochemical properties of the positive electrode material.

Benefits of technology

By doping Li and controlling the Rct/Rf ratio, the cyclic stability and electrochemical performance of the positive electrode material are significantly improved, and the overall performance of the sodium ion battery is enhanced.

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Abstract

The invention relates to the field of batteries, in particular to a sodium ion battery, a positive pole piece for the sodium ion battery, a positive active material, a battery module, a battery pack and a device. The sodium ion battery comprises a positive pole piece, a negative pole piece, an isolating membrane and an electrolyte, the positive pole piece comprises a positive active material, the molecular formula of the positive active material meets NaaLibM0. 7Fe0. 3bO2 + / -delta, M is a transition metal ion, 0.67 lt; a < lt >; 1.1, 0 lt; blt; 0 < = delta < = 0.1, and the ratio Rct / Rf of Rct to Rf of the positive electrode active material satisfies 1.0 lt; rct / Rflt; 20.0, 20.0; wherein Rct and Rf are respectively charge transfer impedance and diffusion impedance obtained by testing the positive electrode active material in the button cell according to an alternating current impedance method. The sodium-ion battery can solve the problem of cycling stability of the positive electrode active material for the current sodium-ion battery, so as to achieve the purpose of improving the cycling performance of the sodium-ion battery.
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Claims

1. A sodium-ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, characterized in that: The positive electrode sheet contains a positive electrode active material, and the molecular formula of the positive electrode active material satisfies Na a Li b M 0.7 Fe 0.3- b O 2±δ , where M is a transition metal ion, 0.67 < a < 1.1, 0 < b < 0.3, 0 ≤ δ ≤ 0.1, and the ratio R ct to R f is R ct / R f with a value satisfying 1.0 < R ct / R f < 20.0; Among them, R ct The charge transfer impedance of the positive electrode active material is obtained by testing the positive electrode active material in a button cell using an AC impedance method; R f It is the diffusion impedance of the positive electrode active material tested in a button cell using an AC impedance method.

2. The sodium-ion battery according to claim 1, characterized in that, the resistance R of the positive electrode sheet ≤ 1000 mΩ, preferably R ≤ 100 mΩ.

3. The sodium-ion battery according to any one of claims 1 to 2, characterized in that, The R ct / R f The value satisfies 1.0 <R ct / R f <18.0, preferably 2.0≤R ct / R f <15.

0.

4. The sodium-ion battery according to any one of claims 1 to 3, characterized in that, In the molecular formula of the positive electrode active material, M is selected from Ni 2+ , Mn 4+ 、Co 2+ , Cu 2+ 、Zn 2+ Mg 2+ or Al 3+ At least one of; Preferably, the M is selected from Ni 2+ 、Co 2+ , Cu 2+ and Mn 4+ At least one of .

5. The sodium-ion battery according to any one of claims 1 to 4, characterized in that, the value of b in the molecular formula of the positive electrode active material is 0.05 < b < 0.2, preferably 0.05 < b < 0.

15.

6. The sodium-ion battery according to any one of claims 1 to 5, characterized in that, The tap density of the positive electrode active material is greater than 1 g / cm 3 , preferably 1.5 to 3 g / cm 3 and / or, The compaction density of the positive electrode active material under 8 tons is 1.5 to 4.5 g / cm 3 , preferably 2.5 to 4 g / cm 3 .

7. The sodium-ion battery according to any one of claims 1 to 6, characterized in that, The average particle size D of the positive electrode active material v 50 is 0.05 to 50 μm, preferably 3 to 30 μm.

8. The sodium-ion battery according to any one of claims 1 to 7, characterized in that, The specific surface area S of the positive electrode active material is 0.01 to 30 m 2 / g, preferably 0.1 to 10 m 2 / g.

9. The sodium-ion battery according to any one of claims 1 to 8, characterized in that, The positive electrode active material R ct / R f , average particle size D v 50(μm) and specific surface area S(m 2 / g)Satisfy: Preferably meet:

10. The sodium-ion battery according to any one of claims 1 to 9, characterized in that, the negative electrode active material in the negative electrode sheet is a carbon material, preferably a hard carbon material; The single-sided positive electrode active material layer density A (g / m 2 ) of the positive electrode sheet and the single-sided positive electrode active material layer B (g / m 2 ) of the negative electrode sheet satisfy: 1.8 < A / B < 2.57, preferably 2.2 < A / B < 2.

47.

11. A positive electrode sheet for a sodium-ion battery, comprising a positive electrode active material layer carried on at least one surface of a positive electrode current collector, and the positive electrode active material layer comprises a positive electrode active material, characterized in that, The molecular formula of the positive electrode active material satisfies Na a Li b M 0.7 Fe 0.3-b O 2±δ , where M is a transition metal ion, 0.67 < a < 1.1, 0 < b < 0.3, 0 ≤ δ ≤ 0.1, and the ratio R ct of R f to R ct / R f satisfies 1.0 < R ct / R f < 20.0; Among them, R ct The charge transfer impedance of the positive electrode active material is obtained by testing the positive electrode active material in a button cell using an AC impedance method; R f It is the diffusion impedance of the positive electrode active material tested in a button cell using an AC impedance method.

12. A positive electrode active material for a sodium-ion battery, characterized in that, The molecular formula of the positive electrode active material satisfies Na a Li b M 0.7 Fe 0.3-b O 2±δ , where M is a transition metal ion, 0.67 <a<1.1,0<b<0.3,0≤δ≤0.1, The positive electrode active material R ct With R f The ratio R ct / R f The value satisfies 1.0 <R ct / R f <20.0; Among them, R ct The charge transfer impedance of the positive electrode active material is obtained by testing the positive electrode active material in a button cell using an AC impedance method; R f It is the diffusion impedance of the positive electrode active material tested in a button cell using an AC impedance method.

13. A battery module, characterized in that, comprises the sodium-ion battery according to any one of claims 1 to 10.

14. A battery pack, characterized in that, comprises the battery module according to claim 13.

15. A device using a sodium-ion battery as a power source, characterized in that, comprises the sodium-ion battery according to any one of claims 1 to 10 or the battery pack according to claim 14.