A hybrid aerogel of Co-Al layered double hydroxide/graphene with three-dimensional porous structure as a novel electrode material for supercapacitors

A three-dimensional (3D) porous hybrid aerogel with a robust interconnected network, which is constructed from cobalt-aluminum layered double hydroxide (Co-Al LDH) nanosheets and graphene, is reported here. The unique character of this hybrid aerogel is that the 3D graphene aerogel (GA) skeleton is incorporated with two-dimensional (2D) Co-Al LDH nanosheets to assemble macroscopic graphene monoliths. Furthermore, the 3D GA in the hybrid aerogel is a scaffold and support for the dispersion of the Co-Al LDH nanosheets, resulting in a relatively loose and open structure within the electrode matrix. When used as a cathode material for supercapacitors, the as-obtained porous Co-Al LDH/graphene hybrid aerogel (Co-Al LDH/GHA) exhibits favorable capacitance and excellent cycling performance, and demonstrates a maximum specific capacitance of 640 F g(-1) at a low current density of 1 A g(-1). This remains at 530 F g(-1) when the current density is increased to 10 A g(-1), and even remains at 305 F g(-1) at a much higher current density of 20 A g(-1). The capacitance keeps at around 97% after 10 000 cycles, demonstrating that the hybrid aerogel has excellent high-current capacitive properties. The enhanced high-current capacitance of this composite benefits from its unique nano-scaled Co-Al LDH with a short diffusion pathway and the excellent electrical conductivity of 3D GA.