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CN-122025637-A - Negative plate and preparation method and application thereof

CN122025637ACN 122025637 ACN122025637 ACN 122025637ACN-122025637-A

Abstract

The application provides a negative plate, a preparation method and application thereof, wherein the negative plate comprises a negative current collector and a negative active coating coated on at least one surface of the negative current collector; the negative electrode active coating comprises composite active particles, sulfide electrolyte and a conductive agent, wherein the composite active particles comprise a core and a coating layer, the core comprises a negative electrode active substance, the coating layer comprises an elastic composite electrolyte, the negative electrode active substance comprises silicon element, and the elastic composite electrolyte comprises nano inorganic electrolyte and polymer electrolyte. According to the application, the elastic composite electrolyte coating layer is formed on the surface of the anode active material, so that the volume expansion of silicon can be inhibited, the reduction decomposition of sulfide electrolyte can be improved, the adhesion strength of the anode active coating layer can be enhanced, and the lithium ion conductivity of the anode piece can be enhanced.

Inventors

  • YU HONGJIANG
  • YU QINGJIANG
  • JIANG KECHENG
  • HAN JINLONG
  • CHEN YIMENG
  • LONG ZHI

Assignees

  • 江苏正力新能电池技术股份有限公司

Dates

Publication Date
20260512
Application Date
20260211

Claims (10)

  1. 1. A negative electrode sheet, characterized in that the negative electrode sheet comprises a negative electrode current collector and a negative electrode active coating coated on at least one surface of the negative electrode current collector; the negative electrode active coating comprises composite active particles, sulfide electrolyte and a conductive agent; wherein the composite active particles comprise a core comprising a negative active material and a coating comprising an elastic composite electrolyte; the negative electrode active material includes a silicon element; the elastic composite electrolyte comprises a nano inorganic electrolyte and a polymer electrolyte.
  2. 2. The negative electrode sheet according to claim 1, wherein the negative electrode active material comprises at least one of nano silicon, silicon carbon, silicon oxide and silicon dioxide, and the mass ratio of the nano inorganic electrolyte in the elastic composite electrolyte is 1% -10%.
  3. 3. The negative electrode sheet of claim 1, wherein the nano-inorganic electrolyte comprises at least one of aluminum titanium lithium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, aluminum lithium germanium phosphate, lithium zirconium oxide; And/or the particle size of the nano inorganic electrolyte is 10 nm-200 nm.
  4. 4. The negative electrode sheet according to claim 1, wherein the polymer electrolyte comprises a polymer ion-conducting agent and a lithium salt, and the mass ratio of the polymer ion-conducting agent to the lithium salt is (3-4): 1; and/or the polymer ion-conducting agent comprises at least one of polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene, polyphenyl ether or polylin; And/or the lithium salt comprises at least one of lithium bis (trifluoromethylsulfonyl) imide, lithium trifluoromethylsulfonyl imide, lithium chloride, lithium tetrafluoroborate, lithium hexafluorophosphate or lithium perchlorate.
  5. 5. The negative electrode sheet of claim 1, wherein the sulfide electrolyte comprises at least one of Thio-LISICON、Li 10 GeP 2 S 12 、Li 10 SnP 2 S 12 、Li 2 S-P 2 S 5 、Li 10 SiP 2 S 12 、Li 2 S-Si 2 S 2 、Li 2 S-B 2 S 3 、Li (7-a) PS (6-a) M a , wherein in Li (7-a) PS (6-a) M a M comprises at least one of Cl, br, F or I, and 0.1≤a≤5.9.
  6. 6. The negative electrode sheet according to any one of claims 1 to 5, characterized in that 50 to 85% of the negative electrode active material, 1 to 10% of the elastic composite electrolyte, 3 to 48.8% of the sulfide electrolyte, and 0.1 to 2% of the conductive agent are included in the negative electrode active coating layer in terms of mass percent.
  7. 7. The method for preparing the negative electrode sheet according to any one of claims 1 to 6, comprising the steps of: S1, mixing and dissolving the polymer electrolyte and a solvent, and then adding the nano inorganic electrolyte to obtain an elastic electrolyte premix; S2, mixing the elastic electrolyte premix into the negative electrode active material through pulse spraying treatment to obtain first slurry; s3, respectively adding the sulfide electrolyte and the conductive agent into the first slurry to perform dispersion treatment to obtain second slurry; S4, coating the second slurry on at least one surface of the negative electrode current collector, and drying to obtain the negative electrode plate.
  8. 8. The method according to claim 7, wherein in S1, the viscosity of the elastic electrolyte premix is 10 mPa-S to 100 mPa-S.
  9. 9. The method according to claim 7, wherein in the pulse jet treatment, the pulse jet pressure is 2mpa to 10mpa, the pulse jet time is 0.1 seconds to 1 second, and the intermittent time is 1 second to 30 seconds.
  10. 10. A solid-state battery comprising a negative electrode sheet, a positive electrode sheet and an electrolyte sheet, wherein the negative electrode sheet is the negative electrode sheet according to any one of claims 1 to 6 or the negative electrode sheet produced by the method according to any one of claims 7 to 9.

Description

Negative plate and preparation method and application thereof Technical Field The application belongs to the field of batteries, and particularly relates to a negative plate and a preparation method and application thereof. Background Solid-state batteries are an important development direction for the next-generation battery technology, and their core features are the use of nonflammable or high-ignition solid-state electrolytes instead of conventional organic liquid electrolytes. This feature of the solid-state battery not only significantly improves the safety performance of the battery system, but also achieves a synchronous increase in the energy density of the system. Therefore, the requirements of fields such as electric vehicles, energy storage systems and the like in the future on the increasing of energy and safety are hopefully met. Among the various new battery systems, solid-state batteries are the next generation of battery technology closest to industrialization, which has become a consensus in the industry and scientific community. Sulfide solid state electrolytes, however, have become an important point of current research and application because of their ionic conductivity comparable to liquid electrolytes. The sulfide solid electrolyte has excellent thermal stability and a wider electrochemical stability window, has good performance in the aspect of safety, and is particularly suitable for application scenes with requirements on high power and wide temperature range performance. However, in constructing an all-solid-state battery system, to achieve the desired energy density advantage, an all-solid-state battery anode typically employs a silicon-containing anode or a lithium metal anode. Although lithium metal anodes have extremely high theoretical capacity, they still face cost, process complexity and long-term safety constraints in practical applications. In comparison, silicon-based anode materials are one of the more feasible technical routes for improving the energy density of batteries at present due to higher specific capacity, relatively mature process basis and better comprehensive cost effectiveness. However, the volume expansion of silicon can cause the problem of particle pulverization of the silicon-based anode material, so that the anode piece is repeatedly cracked in the charge and discharge process, and the anode active coating can possibly be separated from the current collector. On the other hand, when silicon is in contact with sulfide, the reductive decomposition of sulfide electrolyte is aggravated, the resistance of the pole piece may be gradually increased, and active lithium is consumed. The silicon-based negative electrode of high specific capacity may eventually cause degradation of electrochemical performance of the solid-state battery under the influence of the above various reasons. Disclosure of Invention In view of the foregoing, the present application is directed to providing a negative electrode sheet, and a preparation method and application thereof, so as to improve the electrochemical performance of an all-solid-state battery using a silicon-containing negative electrode. In order to solve the technical problems, the application is realized as follows: According to a first aspect of the present application, there is provided a negative electrode sheet comprising a negative electrode current collector and a negative electrode active coating layer coated on at least one surface of the negative electrode current collector, the negative electrode active coating layer comprising composite active particles, a sulfide electrolyte and a conductive agent, wherein the composite active particles comprise a core and a coating layer, the core comprises a negative electrode active material, the coating layer comprises an elastic composite electrolyte, the negative electrode active material comprises a silicon element, and the elastic composite electrolyte comprises a nano inorganic electrolyte, a polymer electrolyte. Preferably, the negative electrode active material comprises at least one of nano silicon, silicon carbon, silicon oxide and silicon dioxide, and the mass ratio of the nano inorganic electrolyte in the elastic composite electrolyte is 1% -10%. Preferably, the nano inorganic electrolyte comprises at least one of Lithium Aluminum Titanium Phosphate (LATP), lithium Lanthanum Zirconium Oxide (LLZO), lithium Lanthanum Titanium Oxide (LLTO), lithium germanium aluminum phosphate (LAGP) and lithium zirconium oxide (Li 2ZrO3), and/or the particle size of the nano inorganic electrolyte is 10 nm-200 nm. Preferably, the polymer electrolyte comprises a polymer ion-conducting agent and lithium salt, wherein the mass ratio of the polymer ion-conducting agent to the lithium salt is (3-4) 1, and/or the polymer ion-conducting agent comprises at least one of polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene, polypheny