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.

Automated summary

In this study, a carbonate-based wide temperature (WT) electrolyte is proposed by combining fluorinated carbonates and fluorobenzene, showing good performance in both low and high temperatures. By adjusting the affinity between solvents and Na+ ions as well as the salt/carbonate ratio, the stability and diffusion properties of the electrolyte are optimized at different temperatures. Additionally, the temperature-responsive solid-electrolyte-interphase induced by the WT electrolyte guarantees the performance of the battery under different temperature conditions.