Search

EP-4738550-A1 - SOLID STATE BATTERY

EP4738550A1EP 4738550 A1EP4738550 A1EP 4738550A1EP-4738550-A1

Abstract

The present invention provides a solid-state battery that is sufficiently excellent in fixing strength between an exterior portion and an external electrode. The present invention relates to a solid-state battery including a battery element, an exterior portion present on an outer surface of the battery element, and an external electrode in contact with the exterior portion, in which the exterior portion includes an oxide ceramic containing: Li (lithium); Mg (magnesium); and one or more elements (M) selected from the group consisting of Group 4 and Group 5 elements, and Bi (bismuth) exists between the exterior portion and the external electrode.

Inventors

  • ISHIZAKI, Hayato

Assignees

  • Murata Manufacturing Co., Ltd.

Dates

Publication Date
20260506
Application Date
20240927

Claims (10)

  1. A solid-state battery comprising a battery element, an exterior portion present on an outer surface of the battery element, and an external electrode in contact with the exterior portion, wherein the exterior portion includes an oxide ceramic containing: Li (lithium); Mg (magnesium); and one or more elements (M) selected from the group consisting of Group 4 and Group 5 elements, and Bi (bismuth) exists between the exterior portion and the external electrode.
  2. The solid-state battery according to claim 1, wherein the external electrode includes Ag (silver).
  3. The solid-state battery according to claim 1 or 2, wherein the external electrode is composed only of Ag.
  4. The solid-state battery according to any one of claims 1 to 3, wherein the oxide ceramic has a rock salt type crystal structure.
  5. The solid-state battery according to any one of claims 1 to 4, wherein the exterior portion has a layer form.
  6. The solid-state battery according to any one of claims 1 to 5, wherein the exterior portion is in direct contact with a surface of the battery element.
  7. The solid-state battery according to claims 1 to 6, wherein the battery element includes a garnet type solid electrolyte.
  8. The solid-state battery according to claim 7, wherein the battery element includes one or more battery constituent units including a positive electrode layer and a negative electrode layer facing each other and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and the solid electrolyte is included in one or more layers selected from the positive electrode layer, the negative electrode layer, and the solid electrolyte layer.
  9. The solid-state battery according to any one of claims 1 to 8, wherein the Bi (bismuth) is segregated between the exterior portion and the external electrode.
  10. The solid-state battery according to claim 9, wherein a portion where the Bi (bismuth) is segregated has a width of 1 to 100 nm.

Description

TECHNICAL FIELD The present invention relates to a solid-state battery. BACKGROUND ART In recent years, the demand for batteries as power sources for portable electronic devices such as mobile phones and portable personal computers has been greatly expanded. In batteries used for such applications, an electrolyte (electrolytic solution) such as an organic solvent has been conventionally used as a medium for moving ions. However, a battery having the above configuration has a risk of leakage of the electrolytic solution. In addition, the organic solvent or the like used as the electrolytic solution is a combustible substance. Therefore, it is required to enhance the safety of the battery. Therefore, in order to enhance the safety of the battery, a solid-state battery using a solid electrolyte as an electrolyte instead of the electrolytic solution has been studied. For example, Patent Documents 1 to 4 propose a solid-state battery having an exterior portion containing an oxide ceramic on an outer surface of a battery element including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer therebetween. PRIOR ART DOCUMENTS PATENT DOCUMENTS Patent Document 1: PCT International Publication No. 2019/167856Patent Document 2: Japanese Patent Application Laid-Open No. 2007-173212Patent Document 3: Japanese Patent Application Laid-Open No. 2003-92092Patent Document 4: PCT International Publication No. 2019/181909 SUMMARY OF THE INVENTION Problem to be solved by the invention However, in the conventional solid-state battery described above, there has been a problem that when firing (for example, 1100°C or more) is performed in the production process thereof, the oxide ceramic included in the exterior portion reacts with the solid electrolyte included in the battery element, the solid electrolyte is decomposed, and a byproduct is generated. Therefore, the exterior portion includes an oxide ceramic containing Li (lithium), Mg (magnesium), and one or more elements (M) selected from the group consisting of Group 4 and Group 5 elements, allowing the reaction with the solid electrolyte to be prevented to some extent, but the following new problem occurs. Specifically, a silica-based additive is commonly used for the external electrode disposed in contact with the exterior portion in order to be bonded, but with only the silica-based additive, a side reaction occurs with the exterior portion, and a defect occurs in the exterior portion. More specifically, a crack was generated at a corner portion of the exterior portion. On the other hand, no additive is added to the external electrode, leading to a problem that a bonding layer is not formed at an interface between the external electrode and the exterior portion, and sufficient fixing strength cannot be obtained therebetween. An object of the present invention is to provide a solid-state battery that is sufficiently excellent in fixing strength between an exterior portion and an external electrode. It is also an object of the present invention to provide a solid-state battery that is sufficiently excellent in fixing strength between an exterior portion and an external electrode although the external electrode does not contain an additive (for example, a silica-based additive). Means for solving the problem The present invention relates to: a solid-state battery having a battery element, an exterior portion covering a surface of the battery element, and an external electrode for drawing electric power generated in the battery element to the outside while being in direct contact with the exterior portion, in whichthe exterior portion includes an oxide ceramic containing: Li (lithium);Mg (magnesium); andone or more elements (M) selected from the group consisting of Group 4 and Group 5 elements, andBi (bismuth) is present between the exterior portion and the external electrode. Advantageous effect of the invention The solid-state battery of the present invention is sufficiently excellent in fixing strength between the exterior portion and the external electrode. BRIEF EXPLANATION OF DRAWINGS FIG. 1 is a schematic view showing an example of a solid-state battery of the present invention, and is a composite view of a perspective view and a sectional view.FIG. 2 is a schematic perspective view showing another example of a solid-state battery of the present invention.FIG. 3A is an example of a schematic sectional view for explaining an interface region between an oxide ceramic constituting an exterior portion and a material constituting an external electrode.FIG. 3B is another example of a schematic sectional view for explaining an interface region between an oxide ceramic constituting an exterior portion and a material constituting an external electrode.FIG. 4A is an example of a schematic view of a TEM photograph showing the presence of Bi atoms when an interface region between an oxide ceramic constituting an exterior portion and a material constitu