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CN-122025545-A - Dry-method battery pole piece, preparation method thereof and lithium ion battery

CN122025545ACN 122025545 ACN122025545 ACN 122025545ACN-122025545-A

Abstract

The invention provides a dry-method battery pole piece, a preparation method thereof and a lithium ion battery. The dry method battery pole piece comprises a self-supporting electrode film, wherein a lithium supplementing layer and a metal current collector layer are sequentially arranged on one side surface of the self-supporting electrode film, and the lithium supplementing layer is positioned between the self-supporting electrode film and the metal current collector layer. The invention realizes the integrated integration of the lithium supplementing function and the current collecting function, solves the two problems of uneven lithium supplementing and weak interface binding force of the traditional dry pole piece, not only remarkably improves the interlayer peeling strength and ensures the mechanical integrity of an electrode structure, but also realizes the lithium supplementing uniformity, finally improves the first coulomb efficiency of the battery, remarkably improves the high-temperature cycle life and the quick charging performance of the battery, and can meet the diversified requirements of new energy automobiles and energy storage systems.

Inventors

  • LIU JIANXI
  • LIU KE
  • LI XUEFA

Assignees

  • 扬州纳力新材料科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260311

Claims (10)

  1. 1. The dry-process battery pole piece is characterized by comprising a self-supporting electrode film, wherein a lithium supplementing layer and a metal current collector layer are sequentially arranged on one side surface of the self-supporting electrode film, and the lithium supplementing layer is positioned between the self-supporting electrode film and the metal current collector layer.
  2. 2. The dry battery pole piece of claim 1, wherein the self-supporting electrode film has an areal density of 100-300g/m 2 ; And/or the thickness of the self-supporting electrode film is 50-200 μm; and/or the self-supporting electrode film comprises the following components in percentage by mass: 80-95% of active material, 3-15% of conductive agent and 2-5% of fiberized binder; the active material comprises any one of ternary active material, silicon-based active material, tin-based active material or graphite active material; And/or, the lithium supplementing layer is a metal lithium layer; and/or the thickness of the lithium supplementing layer is 30-100nm.
  3. 3. The dry method battery pole piece of claim 1, wherein the metal current collector layer is of a gradient structure; Along the direction of keeping away from the benefit lithium layer, metal current collector layer includes transition layer and host layer, and the metal in the transition layer with the lithium in the benefit lithium layer forms the alloy bond.
  4. 4. A dry battery pole piece according to claim 3, characterized in that the metal in the transition layer comprises nickel and/or titanium; and/or the thickness of the transition layer is 5-10nm; and/or the metal in the bulk layer comprises copper or aluminum; and/or the thickness of the main body layer is 5-8 μm; And/or the main body layer is of a porous structure, and the porosity of the main body layer is 15-20%; and/or a protective layer is arranged on the outer surface of the main body layer, and the protective layer comprises an aluminum oxide layer and/or a lithium fluoride layer; the thickness of the protective layer is 10-20nm.
  5. 5. The dry method battery pole piece according to claim 1, wherein a release film is compounded on the outer surface of the metal current collector layer, and the release film is peeled off before a winding or lamination process of battery assembly; The release film comprises a silicon-free fluorine plastic release film or a nano ceramic coating release film; the stripping force of the release film is 8-12g/in.
  6. 6. A method of manufacturing a dry battery pole piece according to any of claims 1-5, comprising the steps of: Providing a self-supporting electrode film as a target substrate; And sequentially preparing a lithium supplementing layer and a metal current collector layer on one side surface of the target substrate to obtain the dry-process battery pole piece.
  7. 7. The method of claim 6, wherein the method of preparing the lithium-compensating layer comprises a magnetron sputtering method; In the magnetron sputtering method, the parameters comprise the sputtering temperature of 20-80 ℃, the sputtering power of 80-200W and the deposition time of 15-60s.
  8. 8. The method of claim 6, wherein ion beam assisted deposition is also introduced during the preparation of the lithium-compensating layer; And/or the metal current collector layer is of a gradient structure, and the gradient structure is prepared by a magnetron sputtering method or a vacuum evaporation method; and/or, the outer surface of the metal current collector layer is compounded with a release film, and the release film is peeled off before the winding or lamination process of battery assembly; The composite technology of the release film comprises a low-temperature rolling method; in the low-temperature rolling method, parameters comprise rolling temperature of 60-80 ℃, pressure of 0.5-1MPa and rolling speed of 5-10m/min.
  9. 9. The preparation method according to claim 6, characterized in that the preparation method comprises the steps of: (1) The self-supporting electrode film is provided as a target substrate and comprises, by mass, 80-95% of an active material, 3-15% of a conductive agent and 2-5% of a fibrous binder, wherein the active material comprises any one of a ternary active material, a silicon-based active material, a tin-based active material or a graphite active material; (2) Sputtering and depositing a metal lithium layer on one side surface of the target substrate by adopting a magnetron sputtering method; When the active material in the self-supporting electrode film is a graphite anode material, the parameters of the magnetron sputtering method comprise inert atmosphere, sputtering temperature of 20-45 ℃, sputtering power of 80-150W, deposition time of 15-30s and thickness of a metal lithium layer of 30-50nm, and argon ion beam assisted deposition with energy of 50-100eV is introduced in the sputtering deposition process; (3) A transition layer and a main body layer are plated on the surface of the metal lithium layer in sequence by adopting a magnetron sputtering method or a vacuum evaporation method, so that a metal current collector layer with a gradient structure is formed; The metal in the transition layer comprises nickel and/or titanium with the thickness of 5-10nm, the metal in the main body layer comprises copper or aluminum with the thickness of 5-8 mu m, the main body layer is of a porous structure, and the porosity of the main body layer is 15-20%; (4) A low-temperature rolling mode is adopted, a release film is compounded on the outer surface of the metal current collector layer, and the release film is peeled off before a winding or lamination process of battery assembly; The low-temperature rolling process comprises the steps of rolling at 60-80 ℃ under 0.5-1MPa at 5-10m/min, wherein the release film comprises a silicon-free fluoroplastic release film or a nano ceramic coating release film, and the stripping force of the release film is 8-12g/in.
  10. 10. A lithium ion battery comprising a dry battery pole piece according to any of claims 1-5.

Description

Dry-method battery pole piece, preparation method thereof and lithium ion battery Technical Field The invention belongs to the technical field of lithium ion batteries, and particularly relates to a dry-method battery pole piece, a preparation method thereof and a lithium ion battery. Background The dry electrode technology has the advantages of environmental protection and high production efficiency because of omitting solvent coating and drying links, and becomes a research hot spot in the field of lithium ion batteries. The self-supporting electrode film is composed of an active material, a conductive agent and a fiberizing binder, and can maintain structural integrity without substrate support, but a plurality of bottlenecks still exist in the aspects of compounding with a current collector and optimizing performance. At present, the combination of a dry electrode and a current collector mainly depends on two modes, namely, firstly, the surface of a metal foil current collector is precoated with conductive adhesive, and then the conductive adhesive is bonded with a self-supporting film through high-temperature hot pressing, the mode not only increases the cost of conductive adhesive materials and the hot pressing process link, but also can introduce extra interface impedance, and secondly, a glue-free composite mode is adopted, but a rolling process with extremely high pressure is needed, so that the structural damage of an active material in the electrode is easy to cause, and the cycle performance of a battery is reduced. Meanwhile, the high specific capacity electrode (such as silicon-based and tin-based negative electrode) has serious irreversible lithium loss in the first charge and discharge process, so that the initial coulombic efficiency and the energy density of the battery are reduced. The existing lithium supplementing technology (such as lithium foil adhesion and lithium-rich additive) is independent of the current collector preparation links, extra process steps are needed, and the cooperative optimization of lithium supplementing uniformity and current collector combination stability is difficult to realize. In summary, the defects of the prior art include 1) poor interfacial adhesion, that is, in the traditional composite mode, the bonding force between a dry electrode and a current collector depends on adhesive layers or mechanical pressure, so that the peeling problem is easy to occur, and the cycle life of a battery is influenced. 2) The process complexity is high, the steps of hot pressing, additional lithium supplementing and the like increase the production flow, reduce the production efficiency and improve the equipment investment cost. 3) The energy density is limited, the thickness of the traditional metal foil current collector is larger (usually 10-15 mu m), the ratio of inactive substances is high, and the improvement of the energy density of the battery is restricted. 4) The lithium supplementing effect is uneven, the uniform distribution of lithium elements on the surface of the electrode is difficult to realize by an independent lithium supplementing process, and the problem of partial lithium excess or deficiency is easy to occur. Therefore, how to solve the problems of weak interface bonding, complex process, low energy density, nonuniform lithium supplementation and the like in the dry-process battery pole piece and realize the integrated integration of the lithium supplementation function and the current collector function is a technical problem to be solved urgently. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a dry-method battery pole piece, a preparation method thereof and a lithium ion battery. The structure design effectively solves the two problems of uneven lithium supplementing and weak interface binding force of the traditional dry pole piece, not only remarkably improves the interlayer peeling strength, ensures the mechanical integrity of an electrode structure, but also realizes lithium supplementing uniformity, finally improves the first coulomb efficiency of the battery, remarkably improves the high-temperature cycle life and quick charging performance of the battery, and can meet the diversified requirements of new energy automobiles and energy storage systems. In order to achieve the aim of the invention, the invention adopts the following technical scheme: In a first aspect, the invention provides a dry-process battery pole piece, which comprises a self-supporting electrode film, wherein a lithium supplementing layer and a metal current collector layer are sequentially arranged on one side surface of the self-supporting electrode film, and the lithium supplementing layer is positioned between the self-supporting electrode film and the metal current collector layer. The structure design effectively solves the two problems of uneven lithium supplementing and weak interface binding force of the traditional