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

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.