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CN-122000295-A - Lithium battery electrode, preparation method thereof and lithium ion battery

CN122000295ACN 122000295 ACN122000295 ACN 122000295ACN-122000295-A

Abstract

The invention relates to the technical field of lithium batteries, in particular to a lithium battery electrode, a preparation method thereof and a lithium ion battery. The electrode comprises a current collector and a composite coating thereon, wherein the coating is formed by combining an outer interface functional layer and an inner current collector functional layer through a middle area of continuous transition of components and a structure. Wherein the interface functional layer adopts active substances with average particle diameter D50 of 1-5 μm and contains conductive agent accounting for 4% -8% of dry weight, and the current collector functional layer adopts active substances with average particle diameter D50 of 8-15 μm and has mass ratio of not less than 94%. The preparation method comprises the steps of sequentially coating the first slurry and the second slurry by using a coating die head to form a composite wet film, drying and rolling. According to the invention, by constructing a continuously graded gradient structure, a clear interface between layers is effectively eliminated, the ion diffusion and electron conduction capacity of the electrode are cooperatively improved, and the multiplying power performance and the cycling stability are obviously improved while the high energy density is maintained.

Inventors

  • LV PENGFEI
  • LI SHAOMIN
  • Tang changyu
  • ZHANG CHUHONG
  • LIU HAO

Assignees

  • 中物院成都科学技术发展中心

Dates

Publication Date
20260508
Application Date
20260213

Claims (10)

  1. 1. A lithium battery electrode, comprising a current collector and a composite coating disposed on the current collector; The composite coating consists of an interface functional layer on the outer side and a current collector functional layer on the inner side in the thickness direction, and an intermediate region with continuous transition of components and structures is formed between the interface functional layer and the current collector functional layer; Wherein, the The interface functional layer comprises a first active substance with an average particle diameter D50 of 1-5 mu m and a first conductive agent accounting for 4-8% of the dry weight of the interface functional layer; the current collector functional layer contains a second active material with an average particle diameter D50 of 8-15 mu m, and the mass percentage of the second active material in the dry weight of the current collector functional layer is not less than 94%.
  2. 2. The lithium battery electrode according to claim 1, wherein the interface functional layer is formed by coating and drying a first slurry, and the solid content of the first slurry is 45% -55%; and/or the number of the groups of groups, The current collector functional layer is formed by coating and drying second slurry, and the solid content of the second slurry is 60% -70%.
  3. 3. The lithium battery electrode according to claim 2, wherein the viscosity of the first paste is 3000-6000 mPa s, and/or the viscosity of the second paste is 8000-15000 mPa s.
  4. 4. The lithium battery electrode according to claim 2, wherein the solid component of the first slurry comprises, in mass percent: 90% -94% of first active substance, 4% -8% Of a first conductive agent, 2% -3% Of a first binder.
  5. 5. The lithium battery electrode according to claim 2, wherein the solid component of the second slurry comprises, in mass percent: 96% -98% of second active substance, 1 To 2.5 percent of second conductive agent, And 0.5 to 1.5 percent of second binder.
  6. 6. The lithium battery electrode according to claim 4 or 5, wherein, The first active substance is at least one of nickel cobalt lithium manganate, nickel cobalt lithium aluminate, lithium iron phosphate and lithium-rich manganese-based lithium; the second active material is at least one of nickel cobalt lithium manganate, nickel cobalt lithium aluminate, lithium iron phosphate and lithium-rich manganese-based lithium; and/or the number of the groups of groups, The first conductive agent is at least one of carbon nano tube, graphene, carbon fiber and conductive carbon black, The second conductive agent is at least one of conductive carbon black, acetylene black and ketjen black; and/or the number of the groups of groups, The first binder is at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylate, styrene butadiene rubber and sodium carboxymethyl cellulose, The second binder is at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylate, styrene butadiene rubber and sodium carboxymethyl cellulose.
  7. 7. The method for preparing an electrode for a lithium battery according to any one of claims 1 to 6, comprising the steps of: Coating the second slurry on a current collector by using a coating die head to form a bottom wet film; applying a first slurry over the underlying wet film; Drying; And rolling the dried pole piece.
  8. 8. The method according to claim 7, wherein the drying treatment is gradient drying, comprising drying at a temperature of 70-90 ℃ and a wind speed of 8-15 m/s in a first temperature zone, followed by drying at a temperature of 100-130 ℃ and a wind speed of 3-8 m/s in a second temperature zone.
  9. 9. The method of claim 8, wherein the compacted density of the pole piece is 2.4-3.2 g/cm 3 after rolling.
  10. 10. A lithium ion battery comprising the lithium battery electrode according to any one of claims 1-6 or the lithium battery electrode prepared by the preparation method according to any one of claims 7-9.

Description

Lithium battery electrode, preparation method thereof and lithium ion battery Technical Field The invention relates to the technical field of lithium batteries, in particular to a lithium battery electrode, a preparation method thereof and a lithium ion battery. Background Along with the continuous improvement of the battery performance requirements of electric automobiles and high-end energy storage systems, the development of lithium ion batteries with high energy density and high power density becomes an industry core challenge. Currently, the most direct technical path for increasing the energy density of the battery is to increase the electrode thickness and active material loading, but this inevitably lengthens the transport path of ions and electrons inside the electrode. In the process of high-current charge and discharge, severe concentration polarization and electrochemical polarization can occur in the electrode, especially in the region far away from the diaphragm and the current collector, so that the effective capacity is rapidly reduced, the voltage platform is attenuated, heating is increased, and the cycle life is rapidly prolonged. The thick electrode effect has become a fundamental bottleneck that restricts the battery from achieving coexistence of fast charge and high energy density. To solve this problem, the prior art has sought a breakthrough in material modification (e.g., synthesis of highly conductive active materials) or electrolyte optimization. However, these methods often only bring marginal improvements and may introduce new problems of cost, stability or safety. From the electrode structure itself, the conventional homogeneous coating design has inherent limitations in principle that the single components and pore distribution cannot simultaneously meet the differential requirements of the electrode surface layer (requiring rapid ion response) and the bottom layer (requiring high-load storage) on the microstructure and the conductive network. Therefore, the lithium battery electrode which can essentially cooperate with the internal ion transmission dynamics and the electron conduction network of the thick electrode and effectively improve the long-term circulation structure stability is constructed, and has very important significance. Disclosure of Invention The invention aims to overcome the defects that the traditional thick electrode in the prior art has serious polarization effect caused by overlong ion/electron transmission path and a homogeneous electrode structure cannot cooperatively optimize rapid ion response and high-load storage, and discloses a lithium battery electrode, a preparation method thereof and a lithium ion battery. The invention provides a gradient functionalized electrode, which is characterized in that a composite coating consisting of an outer interface functional layer and an inner current collector functional layer is constructed on a current collector, a middle area with a continuous transition between components and a structure is formed between the two layers, and the prepared electrode is enabled to remarkably improve the power density and long-cycle stability of a battery while keeping high electrode loading and energy density by controlling the particle size of active substances and the material ratio in the coating. The invention provides a lithium battery electrode, which comprises a current collector and a composite coating arranged on the current collector, wherein the composite coating consists of an interface functional layer on the outer side and a current collector functional layer on the inner side in the thickness direction, and an intermediate region with continuously transitional components and structures is formed between the two layers; wherein the interface functional layer comprises a first active substance with an average particle diameter D50 of 1-5 mu m and a first conductive agent accounting for 4-8% of the dry weight of the interface functional layer; the current collector functional layer contains a second active material with an average particle diameter D50 of 8-15 mu m, and the mass percentage of the second active material in the dry weight of the current collector functional layer is not less than 94%. The invention provides a lithium battery electrode, which comprises a current collector and a composite coating arranged on the current collector, wherein the composite coating is formed by an interface functional layer on the outer side and a current collector functional layer on the inner side in the thickness direction, a middle area with components continuously transiting with a structure is formed between the two layers, the interface functional layer comprises a first active substance with an average particle diameter D50 of 1-5 mu m and a first conductive agent accounting for 4-8% of the dry weight of the interface functional layer, the current collector functional layer comprises a second active substance wit