Synthesis of large-size bulk hierarchically graphene-structured porous carbon and its versatile applications as hosts of sulfur and lithium for Li-S full cells and electrocatalyst for water splitting

Abstract

Three-dimensional (3D) graphene has the advantage of non-agglomeration. However, currently prepared 3D graphene products are generally in powder form, while structured 3D graphene materials are desired for many applications. Here, large-size graphene-structured porous carbon (BGPC) is prepared by injecting polymer, and blowing agent into carbon felt and subsequent heat treatment. Due to the continuous structure, the BGPC offers good mechanical strength with a controllable porous structure, which can be used as electrode host materials for electrochemical applications. When used for Li-S cells, the BGPC cathode with sulfur loading of 5.0 mg/cm2 can be cycled 400 times at 1 C with a good capacity retention of 84.7% in a half cell. When used as the host for lithium metal, the obtained anode can be cycled 1000 times at 5 mA/cm2 with an area capacity of 4 mAh/cm2 in a symmetrical cell. The assembled lithium-sulfur full cell exhibits excellent cycling stability and a high area capacity of 5.6 mAh/cm2. Moreover, the BGPC containing Ni and Mo2C possesses outstanding HER performance with impressively low overpotentials of 99 and 188 mV to generate 100 and 500 mA/cm2, which is superior to the reported catalysts.