Halide-Stabilized LiBH4, a Room-Temperature Lithium Fast-Ion Conductor

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• 作者：Hideki Maekawa ; Motoaki Matsuo ; Hitoshi Takamura ; Mariko Ando ; Yasuto Noda ; Taiki Karahashi ; Shin-ichi Orimo
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：January 28, 2009
• 年：2009
• 卷：131
• 期：3
• 页码：894-895
• 全文大小：166K
• 年卷期：v.131,no.3(January 28, 2009)
• ISSN：1520-5126

文摘

Solid state lithium conductors are attracting much attention for their potential applications to solid-state batteries and supercapacitors of high energy density to overcome safety issues and irreversible capacity loss of the currently commercialized ones. Recently, we discovered a new class of lithium super ionic conductors based on lithium borohydride (LiBH₄). LiBH₄ was found to have conductivity as high as 10⁻² Scm⁻¹ accompanied by orthorhombic to hexagonal phase transition above 115 °C. Polarization to the lithium metal electrode was shown to be extremely low, providing a versatile anode interface for the battery application. However, the high transition temperature of the superionic phase has limited its applications. Here we show that a chemical modification of LiBH₄ can stabilize the superionic phase even below room temperature. By doping of lithium halides, high conductivity can be obtained at room temperature. Both XRD and NMR confirmed room-temperature stabilization of superionic phase for LiI-doped LiBH₄. The electrochemical measurements showed a great advantage of this material as an extremely lightweight lithium electrolyte for batteries of high energy density. This material will open alternative opportunities for the development of solid ionic conductors other than previously known lithium conductors.