Rational design of yolk–shell silicon dioxide@hollow carbon spheres as advanced Li–S cathode hosts

Abstract

Short cycle life and low Coulombic efficiency, in conjunction with fast self-discharge, render lithium–sulfur batteries impractical for commercial applications. In this work, we demonstrated that a “yolk–shell” structure with a polar silicon dioxide (SiO₂) core in a hollow carbon sphere (SiO₂@HC) acts as a highly efficient sulfur host. Such nanoarchitecture benefits from both a physical barrier and chemical adsorption via a carbon shell and a polar SiO₂ core. Furthermore, the internal void space could buffer the huge volume expansion of active sulfur during lithiation. The resulting SiO₂@HC/S composite exhibits a high mass S loading (∼76 wt%), high initial specific capacity of 1200 mA h g⁻¹ at 0.2C, superior rate performance (728 mA h g⁻¹ at 3C), ultraslow capacity decay of 0.056% per cycle at a high rate of 2C and an extraordinary anti-self-discharge feature.