Membranes for rechargeable lithium sulphur semi-flow batteries

The aim of achieving high-energy, long-life, safe and low cast storage batteries has brought tremendous scientific attention in the last decade, resulting in significant improvements in the stored energy of cathodes and anodes particularly in lithium-based battery technology. However, presently available lithium-ion technology cannot satisfy the increasing demand for energy density. Li–S battery is a typical example, which can offer theoretically a fivefold increase in energy density compared with conventional lithium rechargeable batteries. Despite significant advances, there are challenges to its wide-scale implementation, which include dissolution of intermediate polysulphide reaction species into the electrolyte when liquid polysulphide is used as cathodes. Another problem is preparation of polysulphides. Here we report a novel approach to replace the liquid electrolyte with solid lithium conducting membranes, Argyrodite (Li₆PS₅X(X = Cl,Br)) and Li₁₀GeP₂S₁₂ solid electrolytes to mitigate the problem. Among the three solid electrolyte membranes Li₁₀GeP₂S₁₂ exhibited high first discharge specific capacity of 1435 (±3) mAh g⁻¹ at 0.5 C rate.