Temperature-responsive solid-electrolyte-interphase enabling stable sodium metal batteries in a wide temperature range

Sodium metal batteries (SMBs) are currently investigated as an alternative technology to lithium-ion batteries for stationary energy storage systems. However, operation of organic liquid electrolyte-based SMBs has been confined at room temperature, due to the deteriorated performance at elevated or subzero temperatures. Herein, we demonstrate a carbonate-based wide temperature (WT) electrolyte via collaborating the fluorinated carbonates and fluorobenzene. Specifically, fluorinated carbonates weaken the affinity between solvents and Na+ ions, thus accelerate de-solvation process at subzero temperature. Introduction of non-solvating fluorobenzene increases the salt/carbonate ratio, which effectively diminishes the electrolyte degradation at elevated temperature. Furthermore, the temperature-responsive solid-electrolyte-interphase, induced by the WT electrolyte in-situ, can guarantee sufficient Na+ ion diffusion at low temperature and effective passivation for highly reactive sodium metal at elevated temperature. Na/Na3V2(PO4)3 cells based on the WT electrolyte can withstand the temperature interval between −20 and 60 ℃. This proposed WT electrolyte design offers an encouraging path towards all-climate SMBs.