Metal-Organic Framework Separator as a Polyselenide Filter for High-Performance Lithium-Selenium Batteries

Rapid self-discharge, poor cycling stability, and low Coulombic efficiency from polyselenide shuttling have retarded practical applications of lithium-selenium batteries. Here, we show that a cation-selective PCN separator of PCN-250(Fe) metal-organic frameworks coated on a porous polypropylene membrane suppresses polyselenide shuttle and enhances lithium-ion transport in lithium-selenium batteries. The Lewis acid sites of this PCN separator acted as selective barriers that immobilized polyselenides and provided uniform and stable lithium nucleation and growth during cycling. Lithium-selenium cells with the PCN separator had a stable and reversible electrochemical performance with a high discharge capacity of 423 mAh/g at C/5 and a Coulombic efficiency of >98% for 500 cycles. This work provides a guide for developing high-performance lithium-selenium batteries by a cation-selective separator strategy. This PCN separator can be applied to alkali-metal and alkali-metal chalcogenide battery systems.