Interfacial architectures based on a binary additive combination for high-performance Sn4P3 anodes in sodium-ion batteries

Abstract

We demonstrate the important strategy to design suitable electrolyte systems that make the desirable interfacial structure to allow the reversible sodiation/desodiation of Sn₄P₃ anodes. Our investigation reveals that the remarkable improvement in the electrochemical performance of Sn₄P₃ anodes for NIBs is achieved by the combination of fluoroethylene carbonate (FEC) with tris(trimethylsilyl)phosphite (TMSP). We clearly present the unique functions of this binary additive combination to build up a protective surface film on the Sn₄P₃ anode against unwanted electrolyte decomposition and to prevent the formation of the Na₁₅Sn₄ phase, which is accompanied by a large volume expansion during the Na insertion (sodiation) process.