Synthesis of sulfur encapsulated 3D graphene sponge driven by micro-pump and its application in Li–S battery

Because of advantages such as excellent conductivity and high theoretical specific surface area, 3D graphene sponge (3D-GS) grown on Ni template via chemical vapor deposition (CVD) is receiving increasing attention as a conducting template to improve the conductivity of electrode in lithium sulfur (Li–S) battery. However, loading sulfur on the surface of 3D-GS is not a feasible approach to remit the dissolution of polysulfides in cathodes or improve the cycling of batteries. Here, we report a novel design inspired from micro-pump and synthesize a sulfur encapsulated 3D graphene sponge ([email protected]) material for Li–S battery for the first time. Under the oil–water two phase liquid seal system, consisting of sulfur-containing organic phase and etching water phase, the vacuum cavities would generate from Ni etching. Tactfully, the pressure differences between vacuum cavities and sulfur-containing solution were converted into driving force for pumping the sulfur-containing solution into 3D-GS. As a result, the sulfur particles uniformly anchored on the inner surface of 3D-GS after the volatilization of sulfur-containing solution. Serving [email protected] as cathode material does not require any additional conducting additives, current collector or binders thus increasing the loading contents of sulfur. A Li–S battery with [email protected] material cathode shows good electrochemical stability and high rate discharge capacity retention for up to 160 discharge/charge cycles at a high rate of 1C. Our results demonstrate the promising suitability of [email protected] for efficient and high performance rechargeable Li–S batteries.