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

Abstract

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.