A matryoshka-like CuS@void@Co3O4 double microcube-locked sulfur as cathode for high-performance lithium-sulfur batteries

Lithium-sulfur battery cathodes still remain a challenge on capacity decay due to the shuttle effect even though a series of strategies have been tried. Here we report a novel matryoshka-like CuS@void@Co 3 O 4 architecture of double micro-cubes ( μ -cubes) that locks sulfur between the CuS core and the Co 3 O 4 shell. Plenty of existing spaces between the μ -cubes suffice a high loading of sulfur and volumetric accommodation. The robust, double closed cubes configuration greatly enhances the confinement of polysulfides . In parallel, the CuS core increases the electronic conductivity and contributes to additional capacity, while the Co 3 O 4 shell ensures a better interface activity. A high Li +  ion diffusion coefficient is obtained during the sulfur and lithium sulfide transformation. The constructed battery displays an initial capacity up to 1480 mAh g −1 , and a Coulombic efficiency (CE) exceeding 99%. A capacity retention higher than 500 mAh g −1 with a CE larger than 99.8% after cycling 400 times at 0.2 C are achieved. In addition, under a temperature of −5 °C, a high capacity of 700 mAh g −1 at 0.2 C after 200 cycles is achieved, indicating a good low-temperature tolerance.