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

Herein, a novel hybrid S@MnO 2 @C nanosphere, comprising sulfur nanoparticles encapsulated by a MnO 2 @C hollow dual-shell, is reported. Benefiting from a conductive C outer layer, the S@MnO 2 @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 MnO 2 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@MnO 2 @C electrode shows high capacity, high coulombic efficiency and excellent cycling stability. The S@MnO 2 @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%.