Li+ mobility powered by a crystal compound for fast Li–S chemistry

Abstract

Placing blocking layers between electrodes has shown paramount prospects in suppressing the shuttle effect of Li–S batteries, but the associated ionic transport would be a concurrent obstacle. Herein, we present a Li-based crystal composited with carbon (LiPN₂@C) by a one-step annealing of Li⁺ absorbed melamine polyphosphate, which simultaneously achieves alleviated polysulfide-shuttling and facilitated Li⁺ transport. As a homologous crystal, LiPN₂ with abundant lithiophilic sites makes Li⁺ transport more efficient and sustainable. With a LiPN₂@C-modified separator, the Li₂S cathode exhibits a much-lower activation potential of 2.4 V and a high-rate capacity of 519 mA h g⁻¹ at 2C. Impressively, the battery delivers a capacity of 726 mA h g⁻¹ at 0.5C with a low decay rate of 0.25% per cycle during 100 continuous cycles.