Improving the cycling stability of lithium–sulfur batteries by hollow dual-shell coating

Abstract

Herein, a novel hybrid S@MnO₂@C nanosphere, comprising sulfur nanoparticles encapsulated by a MnO₂@C hollow dual-shell, is reported. Benefiting from a conductive C outer layer, the S@MnO₂@C hybrid nanosphere provided highly efficient pathways for fast electron/ion transfer and sufficient free space for the expansion of the encapsulated sulfur nanoparticles. Moreover, the dual-shell composed of a MnO₂ inner layer and a C outer layer coating on S not only improved the efficacious encapsulation of sulfur, but also significantly suppressed the dissolution of polysulfides during cycling. As a result, the S@MnO₂@C electrode shows high capacity, high coulombic efficiency and excellent cycling stability. The S@MnO₂@C cathode delivered a discharge capacity of 593 mA h g⁻¹ in the fourth cycle and was able to maintain 573 mA h g⁻¹ after 100 charge–discharge cycles at 1.0C, corresponding to a capacity retention of 96.6%.