A Strategy for Polysulfides/Polyselenides Protection Based on Co 9 S 8 @SiO 2 /C Host in Na‐SeS 2 Batteries

Abstract To obtain unbroken sulfides with delicate morphology from metal–organic frameworks (MOFs), a method for in situ growth of SiO 2 protective layers on the surface of MOFs is proposed. This strategy can be successfully expanded to a variety of MOFs (ZIF‐67, Cu‐MOF, ZIF‐8, and PBA). Importantly, room‐temperature Na‐SeS 2 batteries with Co 9 S 8 @SiO 2 /C prepared from ZIF‐67 as cathode host are assembled. Due to the hollow structure that can relieve the volume expansion and the co‐adsorption of sodium polysulfides/sodium polyselenides by Co 9 S 8 @SiO 2 /C, the SeS 2 /Co 9 S 8 @SiO 2 /C cathode shows excellent rate performance and Coulombic efficiency. In addition, ex situ X‐ray diffraction and in situ Raman results show that S 8 and Se 8 are generated after the discharge of SeS 2 , and Se 8 is preferentially oxidized during charging.