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JP-7856041-B2 - Method for manufacturing a solid-state battery, and negative electrode active material layer

JP7856041B2JP 7856041 B2JP7856041 B2JP 7856041B2JP-7856041-B2

Inventors

  • 古屋 遼介
  • 吉田 淳

Assignees

  • トヨタ自動車株式会社

Dates

Publication Date
20260511
Application Date
20230420

Claims (7)

  1. To provide silicon particles treated with hydrogen fluoride, The silicon particles, binder, and solid electrolyte are dispersed in an organic solvent to obtain a negative electrode mixture slurry. The negative electrode mixture slurry is applied to a substrate, then dried to obtain a negative electrode active material layer, and the negative electrode active material layer and the solid electrolyte layer are laminated and pressed. It includes, The ratio of the mass of the binder in the negative electrode active material layer to the mass of the silicon particles is 0.6% by mass to 3.0% by mass, and the roll press pressure in the press is 1.0 t/cm or more. A method for manufacturing solid-state batteries.
  2. The method according to claim 1, wherein the roll press pressure is 1.2 t/cm to 2.5 t/cm.
  3. The method according to claim 1, wherein the aforementioned proportion is 1.0% by mass to 2.0% by mass.
  4. The method according to claim 1, wherein the negative electrode mixture slurry is applied to the substrate so that the basis weight is 5.0 mg/ cm² to 10.0 mg/ cm² .
  5. The material comprises a porous silicon clathrate, a binder, and a solid electrolyte, wherein the ratio of the mass of the binder to the mass of the porous silicon clathrate is 0.6% by mass to 3.0% by mass. The negative electrode active material layer, The resistance is 150 Ω·cm² or less. The porous silicon clathrate does not have silicon oxide on its surface. Negative electrode active material layer .
  6. The negative electrode active material layer according to claim 5, wherein the aforementioned ratio is 1.0% by mass to 2.0% by mass.
  7. A negative electrode active material layer comprising the negative electrode active material layer according to claim 5 or 6, and having a resistance of 150 Ω· cm² or less, solid state battery.

Description

This disclosure relates to a method for manufacturing a solid-state battery and to a negative electrode active material layer. In recent years, battery development has been booming. For example, the automotive industry is developing batteries for electric vehicles and hybrid vehicles. Furthermore, silicon is known as an active material used in batteries, particularly lithium-ion batteries. For example, Patent Document 1 discloses an active material for use in an all-solid-state battery, which contains at least Si, and in an infrared spectroscopic spectrum, when the maximum peak intensity at 900 cm⁻¹ to 950 cm⁻¹ is defined as I₁ and the maximum peak intensity at 1000 cm⁻¹ to 1100 cm⁻¹ is defined as I₂ , I₁ and I₂ satisfy the following conditions: 0.55 ≤ I₂ / I₁ ≤ 1.0 and 0.01 ≤ I₁ . Patent Document 2 discloses an all-solid-state battery in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are stacked in this order, wherein the negative electrode layer contains a negative electrode active material having a silicon clathrate type II crystalline phase, the all-solid-state battery is subjected to a constraining pressure of 0 MPa or more and less than 5 MPa in the stacking direction, and the specific surface area of the negative electrode active material is 8 m² /g or more and 17 m² /g or less. Japanese Patent Publication No. 2022-077326Japanese Patent Publication No. 2022-092725 The embodiments of this disclosure will be described in detail below. However, this disclosure is not limited to the embodiments described below, and can be implemented in various modified forms within the scope of the essence of the disclosure. Method for manufacturing solid-state batteries The present disclosure's method for manufacturing a solid-state battery includes providing silicon particles treated with hydrogen fluoride, dispersing the silicon particles, binder, and solid electrolyte in an organic solvent to obtain a negative electrode mixture slurry, applying the negative electrode mixture slurry to a substrate and then drying it to obtain a negative electrode active material layer, and laminating and pressing the negative electrode active material layer and the solid electrolyte layer. Furthermore, the present disclosure's method for manufacturing a solid-state battery is characterized in that the ratio of the mass of the binder in the negative electrode active material layer to the mass of the silicon particles is 0.6% by mass to 3.0% by mass, and the roll press pressure during pressing is 1.0 t/cm or more. According to the method disclosed herein, by using silicon anode active material particles treated with hydrogen fluoride, it is possible to reduce electrical resistance while improving the strength of the anode active material layer having such silicon anode active material particles. While not limited to theory, this is thought to be because, by combining silicon anode active material particles treated with hydrogen fluoride—that is, silicon anode active material particles from which at least partially the oxygen on the surface has been removed—with an appropriate amount of binder and appropriate pressing pressure (roll pressing pressure), it is possible to provide appropriate strength to the anode active material layer having these silicon anode active material particles while utilizing the advantage of low resistance provided by the hydrogen fluoride-treated silicon anode active material particles. Furthermore, in this disclosure, "solid-state battery" means a battery that uses at least a solid electrolyte as its electrolyte. Therefore, a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte. Also, the solid-state battery in this disclosure may be an all-solid-state battery, i.e., a battery that uses only a solid electrolyte as its electrolyte. <Process for supplying silicon particles treated with hydrogen fluoride> A method for manufacturing a solid-state battery according to this disclosure includes providing silicon particles treated with hydrogen fluoride. Such treatment with hydrogen fluoride, particularly treatment with an aqueous hydrogen fluoride solution, can remove silicon oxide from the surface of silicon negative electrode active material particles. While there are no particular limitations on the method for treating silicon particles with hydrogen fluoride, one example is to add an aqueous solution of hydrogen fluoride to water in which silicon particles are dispersed and then mix them. The silicon particles may be porous clathrate silicon. While there are no particular limitations on the method for producing porous silicon clathrate, one example is a method in which silicon and metallic lithium are mixed to obtain a lithium silicon (LiSi) alloy, and the resulting LiSi alloy is reacted with ethanol. <Negative electrode mixture slurry manufacturing process> A method for manufacturing a solid-state battery according to this disclos