A Highly Efficient Ion and Electron Conductive Interlayer To Achieve Low Self-Discharge of Lithium-Sulfur Batteries.

The practical use of lithium-sulfur (Li-S) batteries is limited by serious self-discharge, fast capacity loss, and severe lithium anode erosion due to the shuttling of lithium polysulfides (LiPSs). Herein, we developed a highly efficient ion and electron conductive interlayer composed of Ti ₂ (SO ₄ ) ₃ /carbon composite layer-coated Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ (CLATP) and graphene to effectively block the diffusion of polysulfide anions but allow rapid Li ion transfer, therefore significantly inhibiting the self-discharge and boosting the cyclic stability of Li-S batteries. The Ti ₂ (SO ₄ ) ₃ /carbon thin protective layer endows an optimized adsorption ability toward LiPSs and avoids the side reactions between LATP and LiPSs. The high electronic conductivity of graphene and high ionic conductivity of CLATP ensures the hybrid interlayer rapid electron and fast Li ion transport. As a result, the Li-S battery with the hybrid interlayer shows a high discharge capacity of 671 mAh g ^-1 after 500 cycles with an extremely low capacity fading of 0.022% per cycle at 1 C. Moreover, the battery shows no self-discharge even after rest for 12 days. This work opens up a new way for the design of functional separators to significantly improve the electrochemical performance of Li-S batteries.