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JP-7856894-B2 - Electrode active material for fluoride-ion batteries, electrodes for fluoride-ion batteries, and fluoride-ion batteries

JP7856894B2JP 7856894 B2JP7856894 B2JP 7856894B2JP-7856894-B2

Inventors

  • 柏原 浩大

Assignees

  • 日亜化学工業株式会社

Dates

Publication Date
20260512
Application Date
20220805

Claims (16)

  1. Electrode active material for fluoride-ion batteries containing a complex oxide with a melilite-type crystal structure.
  2. The composite oxide comprises a first metal atom comprising at least one selected from the following first group of metal atoms, a second metal atom comprising at least one selected from the following second group of metal atoms, and a specific nonmetal atom comprising at least one selected from the following specific nonmetal atom group, wherein the specific nonmetal atom comprises at least an oxygen atom, as described in claim 1. First metal atomic group: Li, Be, Na, Mg, K, Ca, Rb, Sr, Y, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi. Second metal atomic group: Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Sn, Hf, Ta, W, Re, Os, Ir, Pt, Au. Specific nonmetallic atomic groups: O, F, N, S, Cl.
  3. The electrode active material for a fluoride-ion battery according to claim 2, wherein the composite oxide has a composition in which the ratio of the total number of moles of the second metal atoms to the total number of moles of the first metal atoms is 1.4 or more and 1.6 or less, and the ratio of the total number of moles of the specified nonmetal atoms to the total number of moles of the first and second metal atoms is 1.3 or more and 1.5 or less.
  4. The electrode active material for a fluoride-ion battery according to claim 2 or 3, wherein the composite oxide comprises at least one selected from the group consisting of Ca, Sr, Y, Ba, and La as the first metal atom.
  5. The electrode active material for a fluoride-ion battery according to claim 2 or 3, wherein the composite oxide comprises at least one selected from the group consisting of Al, Si, Mn, Fe, Co, Ni, Cu, and Ge as the second metal atom.
  6. The electrode active material for a fluoride-ion battery according to claim 2 or 3, wherein the composite oxide comprises at least Sr as the first metal atom.
  7. The electrode active material for a fluoride-ion battery according to claim 2 or 3, wherein the composite oxide comprises at least one selected from the group consisting of Fe and Ge as the second metal atom.
  8. The electrode active material for a fluoride ion battery according to claim 7, wherein the composite oxide has a volume-average particle size of 20 nm or more and 10 μm or less.
  9. The electrode active material for a fluoride ion battery according to claim 1, wherein the composite oxide has a composition represented by the following formula (1). M 1 b M 2 c X d (1) (In formula (1), 1.9 < b < 2.1, 2.9 < c < 3.1, and 6.8 < d < 7.2 are satisfied, and M 1 includes at least one selected from the group consisting of Li, Be, Na, Mg, K, Ca, Rb, Sr, Y, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Bi, M 2 includes at least one element selected from the group consisting of Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Sn, Hf, Ta, W, Re, Os, Ir, Pt, and Au, and X includes O and may further include at least one element selected from the group consisting of N, F, S, and Cl.
  10. The electrode active material for a fluoride ion battery according to claim 9, wherein in formula (1), M1 comprises at least one selected from the group consisting of Ca, Sr, Y, Ba, and La.
  11. The electrode active material for a fluoride ion battery according to claim 9, wherein in formula (1), M2 comprises at least one selected from the group consisting of Al, Si, Mn, Fe, Co, Ni, Cu, and Ge.
  12. The electrode active material for a fluoride ion battery according to claim 9, wherein M1 in formula (1) comprises at least Sr.
  13. The electrode active material for a fluoride ion battery according to claim 9, wherein in formula (1), M2 comprises at least one selected from the group consisting of Fe and Ge.
  14. The electrode active material for a fluoride ion battery according to claim 13, wherein the composite oxide has a volume-average particle size of 20 nm or more and 10 μm or less.
  15. An electrode for a fluoride-ion battery comprising the electrode active material for a fluoride-ion battery described in any one of claims 1 to 3 and claims 9 to 14.
  16. A fluoride-ion battery comprising the electrode for a fluoride-ion battery described in claim 15 and an electrolyte.

Description

This disclosure relates to electrode active materials for fluoride-ion batteries, electrodes for fluoride-ion batteries, and fluoride-ion batteries. Lithium-ion batteries are known as secondary batteries with high energy density. Fluoride-ion batteries have been proposed as batteries capable of achieving even higher energy densities than lithium-ion batteries. For example, Patent Document 1 proposes an active material having a layered perovskite structure and a crystalline phase of a specific composition. Japanese Patent Publication No. 2017-143044 This figure shows an example of the X-ray diffraction spectrum of a composite oxide according to the example.This figure shows an example of a charge/discharge curve for an evaluation battery. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. Furthermore, the content of each component in a composition refers to the total amount of multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component exist in the composition. In addition, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values exemplified as numerical ranges. The embodiments of the present invention will now be described in detail. However, the embodiments shown below are examples of electrode active materials for fluoride-ion batteries, electrodes for fluoride-ion batteries, and fluoride-ion batteries that embody the technical concept of the present invention, and the present invention is not limited to the electrode active materials for fluoride-ion batteries, electrodes for fluoride-ion batteries, and fluoride-ion batteries shown below. Electrode Active Materials for Fluoride-Ion Batteries Electrode active materials for fluoride-ion batteries (hereinafter also simply referred to as "electrode active materials") include composite oxides containing a melilite-type crystal structure. Many conventionally known electrode active materials for fluoride-ion batteries are metallic active materials, which function as active materials through the fluorination and defluorination reaction of metals. The fluorination and defluorination reaction of metals is a reaction that involves a large change in crystal structure, resulting in a large volume change. Therefore, resistance tends to be high, and cycle characteristics and rate characteristics tend to be low. On the other hand, compounds with a layered crystal structure exhibit their function as active materials through the insertion and deinsertion of carrier ions into and out of the interlayer space. Since the crystal structure of the active material does not change, the volume change is small, and a reduction in resistance and improvement in cycle characteristics and rate characteristics can be expected. Composite oxides with a melilite-type crystal structure also have a layered structure, so these advantages can be expected. Generally, composite oxides containing the melilite crystal structure have a theoretical composition represented , for example , by M12M23X7 . Here, M1 represents alkali metals, alkaline earth metals, lanthanides , etc. M2 represents transition metals, Al, Si, Zn, Ge, etc. X represents O, N, F, S, Cl, etc. In the melilite crystal structure, the M2 - X4 tetrahedrons form a two-dimensional network structure, forming a layered structure with the M1 site in between. For information on the composition of the melilite crystal structure, see, for example, International Publication No. 2019/065285. In the melilite crystal structure, excellent cycle and rate characteristics are expected due to the two-dimensional diffusion of fluoride ions. Furthermore, high capacity is expected due to the redox reaction of anions coordinated to the M2 site. The composite oxide containing the melilite-type crystal structure according to this disclosure (hereinafter also simply referred to as "composite oxide") may contain in its composition a first metal atom containing at least one selected from a first group of metal atoms, a second metal atom containing at least one selected from a second group of metal atoms, and a specific nonmetal atom containing at least one selected from a specific nonmetal atom group, including at least an oxygen atom. The composition of the composite oxide may contain only one first metal atom, or a combination of two or more first metal atoms. Furthermore, the composition of the composite oxide may contain only one second metal atom, or a combination of two or more second metal atoms. In addition, the composition of the composite oxide may contain only an oxygen atom as the specific nonmetal atom, or a combination of an oxygen atom and other specific nonmetal atoms. The first group of metal atoms may consist of at least one metal selected