Ionic conductive membrane suitable for sodium metal batteries

Abstract

Recently, sodium-ion batteries have received great attention primarily due to the scarcity of lithium resources and fluctuations in lithium prices, but sodium-ion batteries have relatively low energy densities. One solution to the low energy density is to employ sodium metal anode, and the risks associated with using metallic sodium could be mitigated by constructing sodium-metal batteries (SMBs) with polymer electrolytes. In this paper, we would like to report a novel gel polymer membrane composed of a cellulose polymer, which not only has a wide electrochemical window, but also has excellent mechanical strength and thermal stability. Moreover, the prepared membrane exhibits high ionic conductivity, thus it can be used as separator and/or electrolyte for ionic batteries. The sodium-metal battery constructed with the prepared gel cellulose electrolyte has been further evaluated by cycling at 0.1C and 60 °C. The solid electrolyte interphase (SEI) layer formed on the surface of the sodium metal anode has been carefully examined using various characterization techniques. The results verify that the ionic-liquids based gel polymer electrolyte (IGPE) is thermally and electrochemically stable, and suitable for high-voltage SMBs.