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CN-116365049-B - Secondary battery and electric equipment

CN116365049BCN 116365049 BCN116365049 BCN 116365049BCN-116365049-B

Abstract

The invention discloses a secondary battery and electric equipment, and relates to the technical field of new energy. The secondary battery comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, the positive electrode active material layer comprises tungsten-containing particles, and the distribution density P of the tungsten-containing particles in the positive electrode plate is more than or equal to 31 and less than or equal to 300 per cm 2 . The positive electrode plate contains tungsten-containing particles, which can react with hydrofluoric acid preferentially to release corrosion of hydrofluoric acid to the positive electrode active material body, and which can exist in a tungstic acid form after being corroded and dissolved by hydrofluoric acid, so that a tungstic acid coating layer can be formed on the surface of the positive electrode active material body, and the positive electrode active material body can be effectively protected from being corroded by hydrofluoric acid. Thereby achieving the effect of protecting the positive electrode active material for a long period of time, so that the secondary battery has excellent cycle performance and storage performance.

Inventors

  • CHEN WEI
  • HU YI
  • OUYANG YUNPENG
  • CHU CHUNBO
  • ZHANG YAO

Assignees

  • 欣旺达电动汽车电池有限公司

Dates

Publication Date
20260508
Application Date
20230403

Claims (9)

  1. 1. The secondary battery is characterized by comprising a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, the positive electrode active material layer comprises tungsten-containing particles, and the distribution density P of the tungsten-containing particles in the positive electrode plate is more than or equal to 31 and less than or equal to 300/cm 2 ; the tungsten-containing particles comprise one or more of a tungsten simple substance and WO p 、M 2 WO 4 , wherein p is more than or equal to 2 and less than or equal to 3, and M comprises at least one of Li and Na; the particle size of the tungsten-containing particles is 10-40 mu m.
  2. 2. The secondary battery according to claim 1, wherein the positive electrode active material layer has a compacted density of 2.4 to 3.6g/cm 3 .
  3. 3. The secondary battery according to claim 1, wherein the resistance of the positive electrode tab is 10-300mΩ.
  4. 4. The secondary battery according to claim 1, wherein the peeling force of the positive electrode tab is 5 to 20N/m.
  5. 5. The secondary battery according to claim 1, wherein the mass content of the tungsten-containing particles in the positive electrode active material layer is 0.01% -2.0%.
  6. 6. The secondary battery according to claim 1, wherein the positive electrode active material layer includes a positive electrode active material including Li x Ni y Co z Mn k O 2 , wherein 0.8+.1.1, 0.3< y <1,0< z <1, and 0< k <1.
  7. 7. The secondary battery according to any one of claims 1 to 6, further comprising a negative electrode tab containing transition metal elements Ni, co and Mn in a range of Ni≤600 ppm, co≤120 ppm, mn≤450 ppm when the charge-discharge cycle of the secondary battery is performed until the capacity retention rate becomes 80%, based on the weight of the negative electrode tab.
  8. 8. The secondary battery according to claim 7, wherein the negative electrode tab contains transition metal elements Ni, co and Mn in such a range that Ni≤500 ppm, co≤100 ppm, mn≤380 ppm based on the weight of the negative electrode tab when the secondary battery is stored at 60 ℃ until the capacity retention is equal to 80%.
  9. 9. An electric device, characterized by comprising the secondary battery according to any one of claims 1 to 8 as a power supply source of the electric device.

Description

Secondary battery and electric equipment Technical Field The invention relates to the technical field of new energy, in particular to a secondary battery and electric equipment. Background The key components of the electric automobile are batteries, at present, the lithium ion battery occupies the dominant position of the electric automobile battery market, the lithium ion battery generally comprises a positive electrode, a negative electrode, a diaphragm and electrolyte, wherein the energy density, the safety performance and the service life of the lithium ion battery are directly determined by the performance of the positive electrode material. The ternary positive electrode material becomes a main current positive electrode material in the current market due to higher energy density, but the ternary positive electrode material has poor layered structure stability, is easy to collapse in the repeated charge and discharge process, and the exposed fresh electrode is easy to be corroded by electrolyte byproduct hydrofluoric acid, so that an improvement method is required to be found, and the corrosion of hydrofluoric acid to the positive electrode material body is reduced, so that the electrochemical performance of the ternary positive electrode material is ensured. At present, the conventional method is to coat the ternary positive electrode material, wherein the coating substance comprises metal oxide to reduce direct contact between the positive electrode material and electrolyte, so as to improve long-term performance, but the conventional metal oxide is easy to be corroded by hydrofluoric acid, namely, the protection time of a coating layer for protecting the ternary positive electrode material is limited, and the corrosion protection of the whole life cycle cannot be ensured. Disclosure of Invention The invention aims to solve the technical problems that a coating layer for protecting a ternary positive electrode material in the prior art is easy to be corroded and damaged by hydrofluoric acid, the protection time is short, and the cycle performance and the storage performance of a lithium ion battery are poor. In order to solve the problems, in a first aspect, the invention provides a secondary battery, which comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, the positive electrode active material layer comprises tungsten-containing particles, and the distribution density P of the tungsten-containing particles in the positive electrode plate is 31-300/cm 2. The further technical scheme is that the tungsten-containing particles comprise one or more of tungsten simple substances and WO p、M2WO4, wherein p is more than or equal to 2 and less than or equal to 3, and M comprises at least one of Li and Na. The further technical scheme is that the compaction density of the positive electrode active material layer is 2.4-3.6g/cm 3. The further technical scheme is that the resistance of the positive electrode plate is 10-300mΩ. The further technical proposal is that the stripping force of the positive pole piece is 5-20N/m. According to a further technical scheme, the particle size of the tungsten-containing particles is 10-40 microns, and the mass content of the tungsten-containing particles in the positive electrode active material layer is 0.01% -2.0%. The further technical proposal is that the positive electrode active material layer comprises a positive electrode active material, the positive electrode active material includes Li xNiyCozMnkO2, wherein, x is more than or equal to 0.8 and less than or equal to 1.1, y is more than or equal to 0.3 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1 and 0< k <1. The secondary battery further comprises a negative electrode plate, when the charge and discharge cycle of the secondary battery is carried out and the capacity retention rate is equal to 80%, the negative electrode plate contains transition metal elements of Ni, co and Mn, and the content range of the Ni, co and Mn is less than or equal to 600ppm, co is less than or equal to 120ppm and Mn is less than or equal to 450ppm based on the weight of the negative electrode plate. According to a further technical scheme, when the secondary battery is stored under the condition of 60 ℃ and the capacity retention rate is equal to 80%, the negative electrode plate contains transition metal elements of Ni, co and Mn, and the content range of the Ni, co and Mn is less than or equal to 500ppm, less than or equal to 100ppm and less than or equal to 380ppm based on the weight of the negative electrode plate. In a second aspect, the application discloses an electric device, which comprises the secondary battery, wherein the secondary battery is used as a power supply of the electric device. C