Anti-Perovskite Li-Battery Cathode Materials

Through single-step solid-state reactions, a series of novel bichalcogenides with the general composition (Li 2 Fe) Ch O ( Ch = S, Se, Te) are successfully synthesized. (Li 2 Fe) Ch O ( Ch = S, Se) possess cubic anti -perovskite crystal structures, where Fe and Li are completely disordered on a common crystallographic site (3 c ). According to Goldschmidt calculations, Li + and Fe 2+ are too small for their common atomic position and exhibit large thermal displacements in the crystal structure models, implying high cation mobility. Both compounds (Li 2 Fe) Ch O ( Ch = S, Se) were tested as cathode materials against graphite anodes (single cells); They perform outstandingly at very high charge rates (270 mA g –1, 80 cycles) and, at a charge rate of 30 mA g –1, exhibit charge capacities of about 120 mA h g –1 . Compared to highly optimized Li 1– x CoO 2 cathode materials, these novel anti -perovskites are easily produced at cost reductions by up to 95% and, yet, possess a relative specific charge capacity of 75%. Moreover, these iron-based anti -perovskites are comparatively friendly to the environment and (Li 2 Fe) Ch O ( Ch = S, Se) melt congruently; the latter is advantageous for manufacturing pure materials in large amounts.