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CN-119695062-B - Secondary battery and electric equipment

CN119695062BCN 119695062 BCN119695062 BCN 119695062BCN-119695062-B

Abstract

The invention relates to a secondary battery and electric equipment, and belongs to the technical field of batteries. The secondary battery comprises a positive electrode plate and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active layer arranged on the surface of the positive electrode current collector, the positive electrode active layer comprises a positive electrode active material, the negative electrode plate comprises a negative electrode current collector and a negative electrode active layer arranged on the surface of the negative electrode current collector, the negative electrode active layer comprises a negative electrode active material, the secondary battery meets the condition that Z is more than or equal to 0.14 and less than or equal to 4.67, and Z= (n 1/n 2) is equal to or less than or equal to (p 1/p 2). The secondary battery has good quick charge performance and long cycle life while maintaining high energy density.

Inventors

  • CHEN FUZHOU

Assignees

  • 欣旺达动力科技股份有限公司

Dates

Publication Date
20260508
Application Date
20241216

Claims (10)

  1. 1. The secondary battery is characterized by comprising a positive electrode plate and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active layer arranged on the surface of the positive electrode current collector, and the positive electrode active layer comprises a positive electrode active material; The secondary battery satisfies that Z is more than or equal to 0.14 and less than or equal to 4.67; Wherein z= (n 1/n 2) × (p 1/p 2); n 1/10000 mu m 2 are distribution densities of first active particles in the cross section of the positive electrode active layer, wherein the first active particles are particles with the particle diameter of more than or equal to 8 mu m in the positive electrode active material particles, and n1 is more than or equal to 8 and less than or equal to 36; n 2/10000 mu m 2 are distribution densities of second active particles in the cross section of the positive electrode active layer, wherein the second active particles are particles smaller than 8 mu m in the positive electrode active material particles, and n2 is more than or equal to 6 and less than or equal to 25; p1 is the porosity of the positive electrode active layer, and p1 is more than or equal to 20% and less than or equal to 30%; p2 is the porosity of the anode active layer, and p2 is more than or equal to 35% and less than or equal to 45%.
  2. 2. The secondary battery according to claim 1, wherein the secondary battery satisfies: 1.24≤Z≤2.43。
  3. 3. The secondary battery according to claim 1, wherein the volume ratio of the first active particles to the second active particles per unit volume of the positive electrode active layer is 1 (0.3 to 0.6).
  4. 4. The secondary battery according to claim 1, wherein 0.8≤n1/n2≤6.
  5. 5. The secondary battery of claim 1, wherein the negative electrode tab satisfies at least one of: a. The particle size D v50 of the anode active material is 3-12 mu m; b. The compaction density of the negative electrode active layer is 1.4-1.8 g/cm 3 .
  6. 6. The secondary battery of claim 1, wherein the positive electrode active material comprises a core and a shell layer disposed on a surface of the core, the core comprising a compound having a chemical formula of Li 1+a [Ni x Co y Mn z M b ]O 2 , wherein 0.5≤x <1, 0≤y <0.3, 0≤z <0.3, -0.1≤a <0.2, 0< b <0.3, x+y+z+b= 1;M includes at least one of Ti, zr, sr, sb, nb, ru, pd, Y, ce, W.
  7. 7. The secondary battery according to claim 6, wherein the content of cobalt element presents an increasing trend along the center of the core to the surface of the core.
  8. 8. The secondary battery according to claim 6, wherein the shell layer comprises a metal oxide, and the metal element X in the metal oxide comprises at least one of Al, W, ca, ce, ti, zr, Y.
  9. 9. The secondary battery according to claim 8, wherein the shell layer satisfies 2500≤wXh≤16500; wherein w ppm is the content of the metal element X in the positive electrode active material, and h nm is the thickness of the shell layer.
  10. 10. An electric device, characterized by comprising the secondary battery according to any one of claims 1 to 9 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 batteries, in particular to a secondary battery and electric equipment. Background The positive electrode material is one of key components of the lithium ion battery, and can determine the energy density of the battery to a great extent, wherein the high-nickel layered oxide positive electrode material is widely applied to the field of electric automobiles due to the characteristics of high specific capacity, high voltage platform, high compaction density and the like. However, even the energy density of the high nickel layered oxide positive electrode material is difficult to meet the increasing range demands of people on the power battery. At present, the energy density of the positive electrode material is mainly improved through high nickel or high voltage, but with the increase of nickel content in the positive electrode material, nickel positioned in an octahedron tends to enter lithium sites in a crystal lattice to reduce electrochemical activity of the positive electrode material, and with the high voltage, cracking problems caused by crystal lattice collapse, gas release or structural reconstruction are generated at the same time of realizing high energy density, namely, the high nickel or high voltage can lead to poor cycle stability of the positive electrode material, and further lead to shorter cycle life of a battery. Therefore, there is an urgent need to develop an effective means for maintaining a high energy density of the battery while having good fast charge performance and long cycle life. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide a secondary battery and electric equipment. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: In a first aspect, the invention provides a secondary battery, which comprises a positive electrode plate and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active layer arranged on the surface of the positive electrode current collector, and the positive electrode active layer comprises a positive electrode active material; The secondary battery satisfies that Z is more than or equal to 0.14 and less than or equal to 4.67; Wherein z= (n 1/n 2) × (p 1/p 2); n 1/10000 μm 2 are distribution densities of first active particles in the cross section of the positive electrode active layer, the first active particles being particles of the positive electrode active material particles which are greater than or equal to 8 μm; n 2/10000 μm 2 are the distribution densities of the second active particles in the cross section of the positive electrode active layer, the second active particles being particles smaller than 8 μm in the positive electrode active material particles; p1 is the porosity of the positive electrode active layer; p2 is the porosity of the anode active layer. As an embodiment of the present invention, the secondary battery satisfies that Z≤1.24≤2.43. As an embodiment of the present invention, the volume ratio of the first active particles to the second active particles per unit volume of the positive electrode active layer is 1 (0.3 to 0.6). As an embodiment of the present invention, the n1/n2 satisfies 0.3≤n1/n 2≤7. As an embodiment of the present invention, the secondary battery satisfies at least one of: a. n1 is 8 to 36; b. n2 is 6 to 25; c. p1 is 20% -30%; d. p2 is 35% -45%. As an embodiment of the present invention, the negative electrode tab satisfies at least one of: e. The particle size D v50 of the anode active material is 3-12 mu m; f. The compaction density of the negative electrode active layer is 1.4-1.8 g/cm 3. As an embodiment of the present invention, the positive electrode active material includes a core and a shell layer provided on a surface of the core, the core includes a compound having a chemical formula of Li 1+a[NixCoyMnzMb]O2, wherein 0.5 < x <1, 0< y <0.3, 0< z <0.3, -0.1 < a <0.2, 0< b <0.3, x+y+z+b= 1;M includes at least one of Ti, zr, sr, sb, nb, ru, pd, Y, ce, W. As an embodiment of the present invention, the content of cobalt element presents an increasing trend along the center of the core to the surface of the core. As an embodiment of the present invention, the shell layer includes a metal oxide, and the metal element X in the metal oxide includes at least one of Al, W, ca, ce, ti, zr, Y. The shell layer is 2500-16500, wherein w ppm is the content of the metal element X in the positive electrode active material, and h nm is the thickness of the shell layer. In a second aspect, the present invention provides an electric device, including the above secondary battery, the secondary battery being a power supply of the electric device. Compared with the prior art, the invention has the beneficial effects that: According to the inventi