Search

CN-122025807-A - Secondary battery, battery module, battery pack, and power consumption device

CN122025807ACN 122025807 ACN122025807 ACN 122025807ACN-122025807-A

Abstract

The application provides a secondary battery, which comprises a positive electrode plate and electrolyte, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, the porosity of the positive electrode film layer is P%, the P% is 20-70%, the electrolyte comprises a water removal additive, and the mass percentage of the water removal additive in the electrolyte is a, based on the total mass of the electrolyte, 0.1-1%. The secondary battery of the present application has improved initial Direct Current Resistance (DCR) and high temperature cycle performance while improving porosity to achieve both high energy density and good kinetics. The application also provides a battery module, a battery pack and an electric device comprising the secondary battery.

Inventors

  • HUANG LEI
  • HAN CHANGLONG
  • WU ZELI
  • ZHANG CUIPING
  • WANG FULIN

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20220531

Claims (14)

  1. 1. A secondary battery comprising a positive electrode sheet and an electrolyte, wherein The positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the porosity of the positive electrode film layer is P%, and the P% is 20% -70%; The electrolyte comprises a water removal additive, and the mass percentage of the water removal additive in the electrolyte is a, and the mass percentage of the water removal additive in the electrolyte is 0.1-1% based on the total mass of the electrolyte.
  2. 2. The secondary battery according to claim 1, wherein the secondary battery satisfies 0.2≤a.100/p≤3.5; optionally, the secondary battery satisfies 0.4 +.a.100)/P +.3; more optionally, the secondary battery satisfies 1.0≤a.100/p≤1.7.
  3. 3. The secondary battery according to claim 1 or 2, wherein the water-removing additive comprises at least one selected from the group consisting of a compound of structural formula I, a compound of structural formula II, and an isocyanate-based compound, I is a kind of II (II) Wherein, the R 1 、R 2 、R 3 、R 4 、R 5 and R 6 are each independently of the other a silyl group having a halogen-substituted or unsubstituted alkyl group or a halogen-substituted or unsubstituted alkyl group, and at least one of R 1 、R 2 and R 3 is a silyl group having a halogen-substituted or unsubstituted alkyl group, at least one of R 4 、R 5 and R 6 is a silyl group having a halogen-substituted or unsubstituted alkyl group, Alternatively, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 are each independently of the other a silyl group having unsubstituted C1-C6 alkyl or an unsubstituted C1-C6 alkyl, and at least one of R 1 、R 2 and R 3 is a silyl group having unsubstituted alkyl, at least one of R 4 、R 5 and R 6 is a silyl group having unsubstituted alkyl, Further alternatively, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 are each independently of the other a silyl group having a methyl, ethyl, propyl or butyl group, or a methyl, ethyl, propyl or butyl group, and at least one of R 1 、R 2 and R 3 is a silyl group having a methyl, ethyl, propyl or butyl group, at least one of R 4 、R 5 and R 6 is a silyl group having a methyl, ethyl, propyl or butyl group, And is also provided with X is phosphorus or boron.
  4. 4. The secondary battery according to any one of claims 1 to 3, wherein a is 0.3% to 0.7%.
  5. 5. The secondary battery according to any one of claims 1 to 4, wherein the water-removing additive comprises at least one selected from the group consisting of tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite, diethyltrimethylsilyl phosphite, tris (trimethylsilyl) borate, hexamethylene diisocyanate, trimethylsilyl isocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate.
  6. 6. The secondary battery according to any one of claims 1 to 5, wherein the positive electrode film layer has a porosity p% of 30 to 70%, optionally 30 to 50%.
  7. 7. The secondary battery according to any one of claims 1 to 6, wherein the electrolyte further comprises a film-forming additive, and the mass percentage of the film-forming additive in the electrolyte is b, And the secondary battery satisfies: 0.03≤a/b≤0.7。
  8. 8. The secondary battery according to claim 7, wherein the secondary battery satisfies 0.05≤a/b≤0.5, optionally the secondary battery satisfies 0.15≤a/b≤0.35.
  9. 9. The secondary battery according to claim 7, wherein the film-forming additive comprises at least one selected from adiponitrile, lithium difluorooxalato borate, ethylene carbonate, lithium difluorophosphate, lithium tetrafluoroborate, ethylene carbonate, 1, 3-propane sultone and lithium trifluoromethane sulfonate.
  10. 10. The secondary battery according to any one of claims 1 to 9, wherein the electrolyte includes a lithium salt including at least one selected from lithium hexafluorophosphate, lithium difluorooxalato borate and lithium difluorosulfonimide, and the mass percentage of the lithium salt in the electrolyte is 5 to 18% based on the total mass of the electrolyte.
  11. 11. The secondary battery according to any one of claims 1 to 10, wherein the negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material including at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate.
  12. 12. A battery module comprising the secondary battery according to any one of claims 1 to 11.
  13. 13. A battery pack comprising the battery module of claim 12.
  14. 14. An electric device comprising at least one selected from the secondary battery according to any one of claims 1 to 11, the battery module according to claim 12, and the battery pack according to claim 13.

Description

Secondary battery, battery module, battery pack, and power consumption device The application is based on the application number 202280018808.5, the application date 2022, the month 05 and the day 31, the application number Ningde New energy science and technology Co., ltd, the application name of which is 'secondary battery and preparation method thereof, battery module, battery pack and power utilization device'. Technical Field The present application relates to the field of lithium batteries, and more particularly, to a secondary battery, and a battery module, a battery pack, and an electric device including the same. Background In recent years, along with the wider application range of lithium ion batteries, the lithium ion batteries are widely applied to energy storage power supply systems such as hydraulic power, firepower, wind power, solar power stations and the like, and a plurality of fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like. As lithium ion batteries have been greatly developed, higher demands are also being made on energy density, cycle performance, safety performance, and the like. In designing a high-performance secondary battery, the energy density of the battery can be increased by taking a thicker coating amount, a higher compacted density. With the increase of the coating thickness or the compaction density, the situation that the porosity gradually decreases from the current collector to the surface of the active material occurs, which causes problems of low electrolyte infiltration and absorption efficiency, low lithium ion migration rate, and large internal resistance of the battery, and finally causes the increase of initial Direct Current Resistance (DCR), poor cycle performance, and the like of the battery. By adding the pore-forming agent in the preparation of the positive electrode slurry, the porosity of the pole piece can be regulated, the wettability of the electrolyte in the pole piece can be effectively improved, and the migration speed of lithium ions can be increased. However, the positive electrode sheet of high porosity is liable to absorb water, and thus, unwanted water is inevitably introduced in the battery preparation. In addition, lithium ion battery electrolytes also autocatalytically produce water under high temperature conditions. Such unwanted water in the secondary battery may cause a series of side reactions to rapidly deteriorate the battery performance. Therefore, while increasing the porosity to compromise high energy density and good kinetics, certain strategies need to be taken to reduce unwanted water in the battery, thereby improving the impact of moisture on the initial Direct Current Resistance (DCR) and high temperature cycling performance of the lithium ion battery. Disclosure of Invention The present application has been made in view of the above problems, and an object thereof is to provide a secondary battery that solves the adverse effect of water in the battery on the battery performance while improving the porosity to achieve both high energy density and good kinetics, thereby providing the secondary battery with improved initial Direct Current Resistance (DCR) and high temperature cycle performance, a method of manufacturing the secondary battery, and a battery module, a battery pack, and an electric device including the secondary battery of the present application. In order to achieve the above object, a first aspect of the present application provides a secondary battery comprising a positive electrode sheet and an electrolyte, wherein The positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the porosity of the positive electrode film layer is P%, the P% is 20% -70%, the electrolyte comprises a water removal additive, and the mass percentage of the water removal additive in the electrolyte is a and is 0.1% -1% based on the total mass of the electrolyte. Compared with the prior art, the secondary battery has improved initial Direct Current Resistance (DCR) and high-temperature cycle performance while improving the porosity to achieve both high energy density and good kinetics. In any embodiment, the secondary battery satisfies 0.2≤a.100/p≤3.5, alternatively, the secondary battery satisfies 0.4≤a.100/p≤3.3, more alternatively, the secondary battery satisfies 1.0≤a.100/p≤1.7. By satisfying the above conditions, the initial Direct Current Resistance (DCR) and/or the high temperature cycle performance of the secondary battery can be further improved while ensuring that the secondary battery increases the porosity to give consideration to both high energy density and good kinetics. In any embodiment, the water removal additive comprises at least one selected from the group consisting of a compound of formula I, a