Search

WO-2026094321-A1 - SECONDARY BATTERY

WO2026094321A1WO 2026094321 A1WO2026094321 A1WO 2026094321A1WO-2026094321-A1

Abstract

The present invention comprises a positive electrode layer (14), a negative electrode layer (12), and an electrolyte layer (15) that conducts lithium ions between the positive electrode layer and the negative electrode layer. The positive electrode layer contains a positive electrode active material (14a) that includes Mn in the composition thereof and an oxide ion conductor (14b) that can conduct lithium ions. The electrolyte layer contains a fluorine-containing lithium salt that contains fluorine atoms and a solvent that can dissolve the fluorine-containing lithium salt. The ion conductor is a dielectric that can promote dissociation of lithium ions from the fluorine-containing lithium salt.

Inventors

  • SHIMONISHI YUTA
  • YOSHIDA SHUHEI
  • MASUO YUTA

Assignees

  • 株式会社デンソー

Dates

Publication Date
20260507
Application Date
20250619
Priority Date
20241031

Claims (13)

  1. It comprises a positive electrode layer (14), a negative electrode layer (12), and an electrolyte layer (15) that conducts lithium ions between the positive electrode layer and the negative electrode layer. The positive electrode layer is provided with a positive electrode active material (14a) containing Mn in its composition and an oxide-based ion conductor (14b) having lithium ion conductivity. The electrolyte layer contains a fluorine-containing lithium salt containing fluorine atoms and a solvent capable of dissolving the fluorine-containing lithium salt. The oxide-based ion conductor is a dielectric material that can promote the dissociation of lithium ions from the fluorine-containing lithium salt in a secondary battery.
  2. The secondary battery according to claim 1, wherein the relative permittivity of the oxide-based ion conductor is 90 or higher.
  3. The secondary battery according to claim 1, wherein the oxide-based ion conductor contains an oxyfluoride.
  4. The secondary battery according to claim 4, wherein the acid fluoride has a pyrochlore-type crystal structure and a defect structure.
  5. The secondary battery according to claim 1, wherein the ratio A/B of the area A ( mm² ) of the opposing surfaces of the positive electrode layer and the negative electrode layer with respect to the battery capacity B (mAh) is 30 ( mm² /mAh) or more.
  6. The secondary battery according to claim 1, wherein the positive electrode active material includes LiMn 1-x Fe x PO 4 (where 0 < x < 1). That is the case.
  7. The secondary battery according to claim 6, wherein x in the LiMn 1-x Fe x PO 4 is 0.5 or less.
  8. The secondary battery according to claim 1, wherein the particle size of the oxide-based ion conductor is smaller than the particle size of the positive electrode active material.
  9. The aforementioned negative electrode layer is equipped with a negative electrode active material, The secondary battery according to claim 1, wherein the negative electrode active material includes a silicon-based negative electrode material containing Si.
  10. The secondary battery according to claim 1, wherein the positive electrode layer is a random mixture of particulate positive electrode active material and particulate oxide-based ion conductor.
  11. The secondary battery according to claim 1, wherein the positive electrode layer has an outer surface coated with the oxide-based ion conductor.
  12. The secondary battery according to claim 1, wherein the addition ratio x of the oxide-based ion conductor to the positive electrode active material is 0 wt% < x ≤ 10 wt%.
  13. The secondary battery according to claim 1, wherein the electrolyte layer has an electrolyte (15a) in which a fluorine-containing lithium salt containing LiPF6 is dissolved.

Description

secondary battery Cross-reference of related applications This application is based on Japanese Patent Application No. 2024-192060, filed on October 31, 2024, and its contents are incorporated herein by reference. This disclosure relates to secondary batteries. In recent years, lithium-ion batteries have been developed using mixed materials, such as a mixture of graphite anode material and silicon-based anode material, and a mixture of ternary cathode material and lithium manganese iron phosphate (LMFP) cathode material, in order to achieve higher energy density, lower costs, and higher safety. These mixed materials may contain a large amount of water, such as adsorbed water on the material surface and crystal water embedded within the material's crystal structure. When mixed materials containing a large amount of moisture are used in the manufacture of batteries, if the moisture is not sufficiently removed during the manufacturing process, a small amount of moisture will remain inside the battery. In such batteries, if lithium hexafluoride phosphate ( LiPF6 ), a fluorine-containing lithium salt, is used as the electrolyte, PF5 generated from LiPF6 reacts with moisture, making it easier for hydrogen fluoride (HF) to be generated. The generation of hydrogen fluoride leads to degradation such as the destruction of the SEI (Solid Electrolyte Interface) film, an inert film containing metal at the negative electrode, and metal leaching from the positive electrode active material, reducing the durability of the secondary battery. Patent Document 1 proposes suppressing the generation of hydrogen fluoride by adding an additive to the electrolyte and trapping the PF 5 generated from LiPF 6 . However, in the configuration described in Patent Document 1, the addition of additives to the electrolyte increases the resistance of the electrolyte, resulting in a decrease in the output of the secondary battery. In view of the above points, this disclosure aims to suppress degradation caused by hydrogen fluoride generation from fluorine-containing lithium salts while suppressing a decrease in output in a secondary battery using fluorine-containing lithium salts. To achieve the above objective, one aspect of this disclosure comprises a positive electrode layer, a negative electrode layer, and an electrolyte layer that conducts lithium ions between the positive and negative electrode layers. The positive electrode layer is provided with a positive electrode active material containing Mn in its composition and an oxide-based ion conductor having lithium ion conductivity. The electrolyte layer contains a fluorine-containing lithium salt containing fluorine atoms and a solvent capable of dissolving the fluorine-containing lithium salt. The oxide-based ion conductor is a dielectric material capable of promoting the dissociation of lithium ions from the fluorine-containing lithium salt. This allows the dielectric effect of the oxide-based ion conductor to prioritize the dissociation of lithium ions from fluorine-containing lithium salts, thereby suppressing the generation of hydrogen fluoride from the fluorine-containing lithium salts. Since the oxide-based ion conductor possesses lithium-ion conductivity, it can suppress the decrease in the resistance of the secondary battery while simultaneously suppressing the degradation of the secondary battery caused by hydrogen fluoride generation from the fluorine-containing lithium salts. This is a cross-sectional view showing the configuration of a secondary battery according to an embodiment of the present disclosure.This is a perspective view showing the components of a secondary battery separated.This is a conceptual diagram showing the composition of the positive electrode active material and the oxide-based ion conductor.This is a conceptual diagram showing the composition of the positive electrode active material and the oxide-based ion conductor.This is a conceptual diagram showing the composition of the positive electrode active material and the oxide-based ion conductor.This figure shows the crystal structure of a pyrochlore-type oxide.This diagram shows the manufacturing process for pyrochlore-type oxides.This chart shows the initial resistance and durability of secondary batteries in the examples and comparative examples. The embodiments of this disclosure will be described below with reference to the drawings. Unless otherwise specified, the particle diameter in these embodiments is the particle median diameter D50. The particle median diameter D50 represents the volume-based particle diameter when the volume is integrated from the smallest particle in the particle diameter distribution, reaching 50% of the total particle volume. In other words, the particle median diameter D50 represents the particle diameter corresponding to the median of the particle diameter distribution. The secondary battery 10 of this embodiment is a lithium-ion battery in which lithium ions are conduct