National Institute of Advanced Industrial Science and Technology

Naoki Hamao

Junji Akimoto

Kunimitsu Kataoka

Provided is a complex oxide that has a space group I-43d, has a high hydrogen content, contains almost no impurity phase, exhibits almost no aluminum substitution in the structure thereof, and is suitable for proton conductivity. This complex oxide is represented by a chemical formula LiHLaZrMO(M represents Ta and/or Nb, 3.2&#x3c;x&#x2264;7&#x2212;y, and 0.25&#x3c;y&#x3c;2) and is a single phase of a garnet type structure belonging to a cubic system, and the crystal structure thereof is a space group I-43d.

Proton-conductive complex oxide and fuel cell using same as electrolyte

A solid electrolyte material having high ion conductivity and a all-solid-state lithium-ion secondary battery using this solid electrolyte material are provided. The solid electrolyte material has a garnet-related structure crystal represented by the chemical composition LiLaZrTaNbO(0.05&#x2264;x+y&#x2264;0.2, x&#x2265;0, y&#x2265;0), which belongs to an orthorhombic system and a space group belonging to Ibca. The solid electrolyte material has lithium-ion conductivity at 25&#xb0; C. of at least 1.0&#xd7;10S/cm. Also, in this solid electrolyte material, the lattice constants are 1.29 nm&#x2264;a&#x2264;1.32 nm, 1.26 nm&#x2264;b&#x2264;1.29 nm, and 1.29 nm&#x2264;c&#x2264;1.32 nm, and three 16f sites and one 8d site in the crystal structure are occupied by lithium-ions. The all-solid-state lithium-ion secondary battery has a positive electrode, a negative electrode, and a solid electrolyte, the solid electrolyte comprising this solid electrolyte material.

Solid electrolyte with low-symmetry garnet-related structure and lithium-ion secondary battery

Provided is a complex oxide that has a high hydrogen content, contains almost no impurity phase, and is suitable for proton conductivity. The complex oxide is represented by a chemical formula LiHLaMO(M represents Zr and/or Hf, and 3.2&#x3c;x&#x2264;7) and is a single phase of a garnet type structure belonging to a cubic system. A method for producing the complex oxide includes an exchange step of bringing a raw material complex oxide represented by a chemical formula LiHLaMO(M represents Zr and/or Hf, and 0&#x2264;x&#x2264;3.2) and a compound having a hydroxy group or a carboxyl group into contact with each other to exchange at least some of lithium of the raw material complex oxide and hydrogen of the compound having a hydroxy group or a carboxyl group.

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Tsukuba, Japan

Naoki Hamao