Lithium Fast-Ionic Conduction in Complex Hydrides: Review and Prospects

Complex hydrides exhibit various energy‐related functions such as hydrogen storage, microwave absorption, and neutron shielding. Furthermore, another novel energy‐related function was recently reported by the authors; lithium fast‐ionic conduction, which suggests that complex hydrides may be a potential candidate for solid electrolytes in lithium‐ion batteries. This review presents the recent progress in the development of lithium fast‐ionic conductors of complex hydrides. First, the fast‐ionic conduction in LiBH4 as a result of clarifying the mechanism of microwave absorption is presented, and then the conceptual development of complex hydrides as a new type of solid‐state lithium fast‐ionic conductors in LiBH4–, LiNH2–, and LiAlH4‐based complex hydrides is discussed. Finally, the future prospects of this study from both application and fundamental viewpoints are described: possible use as solid electrolytes for batteries, formation of ionic liquids in complex hydrides, and similarity between complex hydrides and Laves‐phase metal hydrides. Complex hydrides exhibit lithium fast‐ionic conduction (see graphic), which implies that these materials can potentially be used as solid electrolytes for lithium‐ion batteries. In this review, first, fast‐ionic conduction in LiBH4 is presented, and then the conceptual development of complex hydrides is discussed as a new category of solid‐state lithium fast‐ionic conductors, along with future prospects.