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EP-3736828-B1 - SOLID ELECTROLYTE MATERIAL AND BATTERY

EP3736828B1EP 3736828 B1EP3736828 B1EP 3736828B1EP-3736828-B1

Inventors

  • SAKAI, AKIHIRO
  • ASANO, TETSUYA
  • SAKAIDA, MASASHI
  • NISHIO, Yusuke
  • MIYAZAKI, AKINOBU
  • HASEGAWA, SHINYA

Dates

Publication Date
20260513
Application Date
20181113

Claims (10)

  1. A solid electrolyte material represented by the following composition formula (1): Li 6-3d Y d X 6 Formula (1) where X is two or more kinds of elements selected from the group consisting of Cl, Br, and I; and 0 < d < 2 ; wherein the solid electrolyte material represented by composition formula (1) is selected from: (i) a solid electrolyte material represented by the following composition formula (2): Li 6-3d Y d Br 6-x Cl x Formula (2) where 1 ≤ x ≤ 5; (ii) a solid electrolyte material represented by the following composition formula (3): Li 6-3d Y d Br 6-x I x Formula (3) where 1 ≤ x ≤ 5; (iii) a solid electrolyte material represented by the following composition formula (4): Li 6-3d Y d Cl l Br m I n Formula (4) where l + m + n = 6, and wherein 0.5 < I < 5, 0.5 < m < 5, and 0.5 < n < 5 are satisfied.
  2. The solid electrolyte material according to claim 1, wherein 0.3 ≤ d ≤ 1.8 is satisfied.
  3. The solid electrolyte material according to claim 2, wherein 0.5 ≤ d ≤ 1.5 is satisfied.
  4. The solid electrolyte material according to claim 3, wherein 0.9 ≤ d ≤ 1.2 is satisfied.
  5. The solid electrolyte material according to any of claims 1 to 4, wherein, when the solid electrolyte material represented by composition formula (4), 2 ≤ l ≤ 3, 2 ≤ m ≤ 3, and 1 ≤ n ≤ 2 are satisfied.
  6. The solid electrolyte material according to claim 5, wherein, when the solid electrolyte material represented by composition formula (4), l = 2, m = 2, and n = 2 are satisfied.
  7. A battery, comprising: a positive electrode; a negative electrode; and an electrolyte layer provided between the positive electrode and the negative electrode, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer includes the solid electrolyte material according to any one of claims 1 to 6.
  8. The battery according to claim 7, wherein the positive electrode includes: a particle of a positive electrode active material; and an oxide coating at least a part of the particle.
  9. The battery according to claim 8, wherein the positive electrode active material is Li(NiCoAl)O 2 .
  10. The battery according to claim 8, wherein the oxide is LiNbO 3 .

Description

BACKGROUND 1. Technical Field The present disclosure relates to a solid electrolyte material and a battery. 2. Description of the Related Art Patent Literature 1 discloses an all-solid battery using a sulfide solid electrolyte. Patent Literature 2 discloses an all-solid battery using, as a solid electrolyte, a halide including indium. Non-Patent Literature 1 discloses Li3YBr6. XP055600030 and XP055600040 relates to ternary halogenides Li3MBr6 and Li3MCl6. JP2006244734A relates to solid electrolyte materials. CITATION LIST Patent Literature Patent Literature 1: Japanese Patent Application Publication No. 2005-353309Patent Literature 2: Japanese Patent Application Publication No. 2006-244734 Non-Patent Literature Non-patent Literature 1: Z. Anorg. Allg. Chem.623 (1997), 1352 SUMMARY In the prior art, realization of a solid electrolyte material having high lithium ion conductivity is desired. The solid electrolyte material in accordance with the present invention is defined in claim 1. Preferred embodiments are defined in claims 2 to 6. Further, the present invention concerns a battery in accordance with claim 7. Preferred embodiments are defined in claims 8 to 10. According to the present disclosure, a solid electrolyte material having high lithium ion conductivity can be realized. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a schematic configuration of a battery in a second embodiment.FIG. 2 is a schematic diagram illustrating an evaluation method of ionic conductivity.FIG. 3 is a graph showing temperature dependence of the ionic conductivity of solid electrolytes.FIG. 4 is a graph showing an initial discharge characteristic. DETAILED DESCRIPTION OF THE EMBODIMENTS Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. (First embodiment) The solid electrolyte material in the first embodiment is a solid electrolyte material represented by the following composition formula (1):         Li6-3dYdX6     Formula (1). Here, X is two or more kinds of elements selected from the group consisting of Cl, Br, and I; and Further, 0 < d < 2 is satisfied. The crystal structure of the solid electrolyte material described in the first embodiment includes a fundamental structure of LiX (X is two or more kinds of elements selected from the group consisting of Cl, Br, and I). By doping the crystal structure with yttrium cations (Y3+) each having a valence different from that of the lithium cation (Li+) of the fundamental structure so as to satisfy electrical neutrality of the whole of the crystal, vacancies are generated in the crystal structure. Li ions can be conducted in the crystal through the generated vacancies. The symmetry of the crystal structure is varied from the fundamental structure by geometrical element arrangement of Li, Y, and the vacancies in the crystal structure or by balance between the ionic radius of the anion and the ionic radius of the cation. The number of the vacancies is varied, depending on the value of d. For example, if d = 1, two vacancies are present on average for three Li ions. According to the above configuration, a halide solid electrolyte material having high Li ionic conductivity can be realized. In addition, a solid electrolyte material having a stable structure can be realized in the assumed operation temperature range of the battery (for example, within the range of -30 °C to 80 °C). In other words, the solid electrolyte material of the first embodiment does not have a configuration (for example, the configuration of Patent Literature 2) in which the phase transition temperature thereof is present in the operation temperature range of the battery. As a result, even in an environment where there is a temperature change, high ionic conductivity can be stably maintained without causing a phase transition to occur within the operation temperature range of the battery. In addition, according to the above configuration, a solid electrolyte exhibiting high Li ionic conductivity of not less than 1 × 10-4 S/cm can be realized, and an all-solid secondary battery excellent in a charge/discharge characteristic can be realized. Furthermore, by adjusting the composition, Li ionic conductivity of more than 7 × 10-4 S/cm is achieved, and an all-solid secondary battery capable of being charged or discharged more rapidly can be realized. Furthermore, high Li ionic conductivity of not less than 10 × 10-4 S/cm can be realized within a further limited composition region, and a higher performance all-solid secondary battery can be realized. Moreover, by using the solid electrolyte material of the first embodiment, an all-solid secondary battery which does not include sulfur can be realized. In other words, the solid electrolyte material of the first embodiment does not have a configuration (for example, the configuration of Patent Literature 1) in which hydrogen sulfide is generated if exposed to the air. As a result, an all-solid s