Plastic crystalline lithium salt with solid-state ionic conductivity and high lithium transport number

Plastic crystallinity of lithium salt, [LiB(OCH2CH2OCH3)4] (1), and its solid-state ionic conductivity are disclosed. The addition of small amounts of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to borate 1 led to the drastic increase of the ionic conductivity and lithium transport number of the electrolyte.