Lithium-ion battery and apparatus
The present application provides a lithium-ion battery and an apparatus, the lithium-ion battery includes an electrode assembly and an electrolytic solution, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separation film. A positive electrode active material in the positive electrode sheet includes Li x1 Co y1 M 1-y1 O 2-z1 Q z1 , and the positive electrode active material is a mixture of large particles Li x1 Co y1 M 1-y1 O 2-z1 Q z1 and small particles Li x1 Co y1 M 1-y1 O 2-z1 Q z1 ; an average particle size D50 of the large particles Li x1 Co y1 M 1-y1 O 2-z1 Q z1 is 10 μm-17 μm, and an average particle size D50 of the small particles Li x1 Co y1 M 1-y1 O 2-z1 Q z1 is 2 μm-7 μm. The electrolytic solution contains an additive A that is a polynitrile six-membered nitrogen-heterocyclic compound with a relatively low oxidation potential. The lithium-ion battery has superb cycle performance and storage performance, especially under high-temperature and high-voltage conditions.
1. A lithium-ion battery, comprising an electrode assembly and an electrolytic solution, wherein the electrode assembly comprises a positive electrode sheet, a negative electrode sheet, and a separation film; wherein
a positive active material in the positive electrode sheet comprises Li x1 Co y1 M 1-y1 O 2-z1 Q z1 , 0.5≤x1≤1.2, 0.8≤y1<1.0, 0≤z1≤0.1, M is one or more selected from the group consisting of Al, Ti, Zr, Y, and Mg, and Q is one or more selected from the group consisting of F, Cl, and S;
the positive electrode active material comprising Li x1 Co y1 M 1-y1 O 2-z1 Q z1 is a mixture of large particles and small particles, wherein an average particle size D50 of the large particles is 10 μm-17 μm, and an average particle size D50 of the small particles is 2 μm-7 μm;
the electrolytic solution contains an additive A that is one or more selected from the group consisting of compounds represented by Formula I-1 and Formula I-3;
in the Formula I-1 and the Formula I-3, R 1 , R 2 , R 3 , and R 4 each are independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1 -C 12 alkyl group, a substituted or unsubstituted C 1 -C 12 alkoxy group, a substituted or unsubstituted C 1 -C 12 amine group, a substituted or unsubstituted C 2 -C 12 alkenyl group, a substituted or unsubstituted C 2 -C 12 alkynyl group, a substituted or unsubstituted C 6 -C 26 aryl group, or a substituted or unsubstituted C 2 -C 12 heterocyclic group, wherein a substituent group is one or more selected from the group consisting of a halogen atom, a nitrile group, a C 1 -C 6 alkyl group, a C 2 -C 6 alkenyl group, and a C 1 -C 6 alkoxy group;
x, y, and z each are independently selected from integers 0-8; and
m, n, and k each are independently selected from integers 0-2;
wherein based on total mass of the electrolytic solution, a mass percentage of the additive A is 0.1%-3.5%; and
a mass ratio of the large particles to the small particles is 1:1-4:1.
2. The lithium-ion battery according to claim 1 , wherein
in the Formula I-1 and the Formula I-3, R 1 , R 2 , R 3 , and R 4 each are independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1 -C 3 linear or branched alkyl group, a substituted or unsubstituted C 5 -C 7 cyclic alkyl group, a substituted or unsubstituted C 1 -C 3 alkoxy group, a substituted or unsubstituted C 1 -C 3 amine group, a substituted or unsubstituted C 2 -C 3 alkenyl group, a substituted or unsubstituted C 2 -C 3 alkynyl group, a substituted or unsubstituted C 6 -C 8 aryl group, or a substituted or unsubstituted C 2 -C 7 heterocyclic group, wherein a substituent group is selected from halogen atoms;
x, y, and z each are independently selected from 0, 1, or 2; and
m, n, and k each are independently selected from 1 or 2.
3. The lithium-ion battery according to claim 1 , wherein,
in the Formula I-1, R 1 , R 3 , and R 4 are all the same group; and
in the Formula I-3, at least two of R 1 , R 2 , and R 3 are the same group.
4. The lithium-ion battery according to claim 3 , wherein
in the Formula I-1, R 1 , R 3 , and R 4 are each a hydrogen atom; and
in the Formula I-3, at least two of R 1 , R 2 , and R 3 are a hydrogen atom.
5. The lithium-ion battery according to claim 1 , wherein, the additive A is one or more selected from the group consisting of the following compounds:
6. The lithium-ion battery according to claim 1 , wherein the electrolytic solution further contains an additive B, the additive B is LiBF 4 , and based on total mass of the electrolytic solution, a mass percentage of the additive B is 0.1%-5%.
7. The lithium-ion battery according to claim 1 , wherein the electrolytic solution further contains an additive C, and the additive C is one or more selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, and 1,3-propane sultone; based on the total mass of the electrolytic solution, a mass percentage of the additive C is 0.1%-5%.
8. The lithium-ion battery according to claim 1 , wherein the lithium-ion battery is a hard-shell lithium-ion battery or a soft-package lithium-ion battery; an end-of-charge voltage of the lithium-ion battery is 4.35V.
9. An apparatus, comprising the lithium-ion battery according to claim 1 .