Achieving superb sodium storage performance on carbon anodes through an ether-derived solid electrolyte interphase

Abstract

High specific surface area carbon (HSSAC) is a class of promising high-capacity anode materials for sodium-ion batteries (SIBs). A critical bottleneck of the HSSAC anode, however, is the ultra-low initial coulombic efficiency (ICE) in commonly used ester-based electrolytes. This phenomenon further prohibits improving the specific capacity, long-term stability and rate capability of HSSAC anodes. This work reports the largely enhanced anode performance of several different HSSAC anodes in ether-based electrolytes. Very importantly, with the reduced graphene oxide (rGO) anode as one example, the ICE can be as high as 74.6% accompanied by a large reversible specific capacity of 509 mA h g⁻¹ after 100 cycles at a current density of 0.1 A g⁻¹. 75.2% of the capacity was retained after 1000 cycles at 1 A g⁻¹. Even at a high current density of 5 A g⁻¹, the specific capacity of the rGO anode can be obtained at 196 mA h g⁻¹. This extraordinary performance is ascribed to the stable, thin, compact, uniform and ion conducting solid electrolyte interphase (SEI) formed in an ether-based electrolyte. Fortunately, this SEI-modifying strategy is generic and is independent of the specific microstructures of HSSAC anodes, indicating a promising avenue for manipulating the SEI on HSSAC anodes through utilizing ether solvents to enable achievement of high ICE for large-capacity HSSAC anodes for practical applications.