Researchers suggest new basis for lithium batteries

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A team of researchers at Tohoku University in Japan has created a new type of lithium ion conductor and believes this could be the basis for a new generation of solid state batteries.
The approach uses lithium borohydride (LiBH4), a material that has been considered for batteries before, but which has only worked at high temperature or pressure.

Describing their work in APL Materials, the researchers say they doped a cubic lattice of potassium iodide (KI) molecules with LiBH4. This allowed them to stabilise the high pressure form of LiBH4, creating a solid solution at normal atmospheric pressure that was stable at room temperature. In the process, the team discovered that Li+ ions functioned like pure Li+ ion conductors, even though they were only doping the KI lattices. This, they say, is the reverse of the normal doping technique, in which a small amount of stabilising element is added to an ionic conductor abundant in lithium. "In other words," said lead researcher Hitoshi Takamura, "LiBH4 is a sort of 'parasite', but not a host material." Takamura and his colleagues have called this mechanism 'parasitic conduction' and have suggested that it could be broadly applied in the search for new batteries – anywhere that small amounts of Li+ ions could be used to dope an oxide, sulphide, halide or nitride host. "This work suggests the potential of this mechanism in the ongoing search for the perfect material for use in solid state batteries," added Takamura.