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CN-122025636-A - Lithium battery positive plate, preparation method and semisolid lithium battery

CN122025636ACN 122025636 ACN122025636 ACN 122025636ACN-122025636-A

Abstract

The application provides a lithium battery positive electrode plate, a preparation method and a semisolid lithium battery, and belongs to the technical field of lithium batteries; the positive electrode layer comprises a positive electrode active material, a conductive agent, a binder and an additive, wherein the additive comprises a mixture of a solid electrolyte and lithium salt, the additive is distributed in gaps of positive electrode active material particles, and an ion transmission network is formed among the positive electrode active material particles after the additive is subjected to hot pressing treatment. The positive pole piece provided by the embodiment of the application has higher density, the porosity of the pole piece is greatly reduced, and a good ion transmission path is arranged in the pole piece.

Inventors

  • YANG SIMING
  • LI JIA
  • LV JIXIAN
  • YU WEIKE
  • QI XIAOQUN
  • JIA TAO

Assignees

  • 中国电气装备集团科学技术研究院有限公司

Dates

Publication Date
20260512
Application Date
20260206

Claims (10)

  1. 1. The lithium battery positive electrode plate is characterized by comprising a current collector and a positive electrode layer arranged on the surface of the current collector; The positive electrode layer comprises a positive electrode active material, a conductive agent, a binder and an additive, wherein the additive comprises a mixture of a solid electrolyte and lithium salt, the additive is distributed in gaps of positive electrode active material particles, and an ion transmission network is formed among the positive electrode active material particles after the additive is subjected to hot pressing treatment.
  2. 2. The pole piece of claim 1, wherein the additive is present in the positive layer in an amount of 0.5wt% to 8wt%.
  3. 3. The pole piece according to claim 1 or 2, characterized in that the mass ratio of the solid electrolyte and the lithium salt is (60-96): 4-40.
  4. 4. A pole piece according to claim 1 or 2, characterized in that the porosity of the positive layer is less than 15%.
  5. 5. Pole piece according to claim 1 or 2, characterized in that the solid state electrolyte is selected from polymer solid state electrolytes and/or oxide solid state electrolytes, the lithium salt being selected from fluorine-containing lithium salts and/or organic lithium borates.
  6. 6. The pole piece of claim 5, wherein the polymer solid electrolyte is selected from at least one of polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polyacrylonitrile, and polymethyl methacrylate, and the oxide solid electrolyte is selected from at least one of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium lanthanum zirconium titanium oxide, and derivatives thereof.
  7. 7. The pole piece of claim 5, wherein the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium difluoro-oxalato-borate, lithium bis-oxalato-borate, and lithium trifluoro-methanesulfonate.
  8. 8. The preparation method of the semi-solid lithium battery positive electrode plate is characterized by comprising the following steps: mixing an anode active material, a conductive agent and a binder, and then adding a first organic solvent for kneading to obtain a powder mass; dissolving a solid electrolyte and lithium salt in a second organic solvent to obtain an additive solution; adding the additive solution into the powder dough, and stirring to obtain positive electrode slurry; And coating the positive electrode slurry on a current collector, drying and performing hot pressing treatment to obtain the semi-solid lithium battery positive electrode plate.
  9. 9. The method of claim 8, wherein the first organic solvent is N-methylpyrrolidone, and the second organic solvent is one or more of N-methylpyrrolidone, N-dimethylformamide, acetonitrile, ethylene glycol, dimethyl sulfoxide, and propylene carbonate.
  10. 10. A semi-solid lithium battery comprising the positive electrode sheet of a lithium battery according to any one of claims 1-7.

Description

Lithium battery positive plate, preparation method and semisolid lithium battery Technical Field The application relates to the technical field of lithium batteries, in particular to a lithium battery positive plate, a preparation method and a semisolid lithium battery. Background With the continuous increase of the demand of high-energy-density energy storage, the safety performance and the comprehensive performance of lithium batteries are increasingly demanding. Currently, a liquid electrolyte system is commonly adopted in commercial lithium ion batteries, and the liquid electrolyte system internally contains a large amount of flammable and explosive organic solvent components. When the battery encounters extreme working conditions such as external mechanical impact, internal abnormal expansion or thermal runaway, the packaging structure is easy to damage, so that the liquid electrolyte is leaked. The leakage not only causes short circuit risk, but also causes combustion and even explosion accidents extremely easily due to high volatility and combustibility of the organic solvent, thereby seriously threatening the safety of users. To balance high ionic conductivity with intrinsic safety, semi-solid lithium battery technology is becoming the focus of research. In the prior art, in situ solidification strategies reduce the liquid content by converting the liquid electrolyte into a gel state electrolyte, but this process has significant drawbacks. The gel electrolyte has generally insufficient wettability to electrode materials, is difficult to uniformly permeate into active material particles, and causes interruption of lithium ion migration paths, so that the problems of increased internal resistance, reduced rate performance, shortened cycle life and the like of the battery are caused. Meanwhile, the curing reaction is easily interfered by factors such as temperature fluctuation, solvent residue, uneven additive distribution and the like, partial electrolyte cannot be completely converted, and the residual liquid components still remain potential safety hazards. Some technical solutions attempt to directly coat the surface of the electrode material with a solid electrolyte layer, for example, depositing a lithium lanthanum zirconium oxide solid electrolyte material on the outer layers of the positive and negative electrode active particles, and simultaneously coating similar substances on both sides of the separator to form an ion channel. However, such coating process requires additional steps of treatment during the active material synthesis stage, which greatly increases the production cost and the process complexity. More importantly, the coating layer occupies effective space of active substances, so that theoretical gram capacity of the cathode material per unit mass is directly reduced, and the overall energy density of the battery is obviously reduced. In addition, the coating process may destroy the surface structural stability of the active material, accelerating the performance decay of the material in the cycle. Another method adopts a secondary coating process, and a solid electrolyte layer is additionally coated on the surface of the prepared pole piece. The operation not only prolongs the production period and increases the equipment investment, but also reduces the product yield due to the rising of the surface roughness of the pole piece caused by multiple coating. More seriously, obvious physical and chemical property differences exist between the new coating layer and the original pole piece, a high interface impedance area is formed, lithium ion cross-interface migration is hindered, and finally the charge and discharge efficiency and the power output capacity of the battery are affected. The above technical bottlenecks indicate that the conventional semi-solid lithium battery solution still faces serious challenges in terms of simplifying the manufacturing process, maintaining high energy density and optimizing ion transport efficiency, and there is a need to solve such problems. Disclosure of Invention Aiming at the problems in the prior art, the application provides a lithium battery positive plate, a preparation method and a semisolid lithium battery, which solve the problems of difficult manufacturing process, low energy density, non-ideal ion transmission efficiency and the like of the conventional battery. In order to solve the above problems, a first aspect of the present application provides a positive electrode sheet for a lithium battery, including a current collector and a positive electrode layer disposed on a surface of the current collector; The positive electrode layer comprises a positive electrode active material, a conductive agent, a binder and an additive, wherein the additive comprises a mixture of a solid electrolyte and lithium salt, the additive is distributed in gaps of positive electrode active material particles, and an ion transmission network is formed am