Microstructure and electrochemical performance of 3D hierarchical porous graphene/polyaniline composites

Porous graphene materials show outstanding performance in energy storage field due to their unique microstructure and properties. To construct 3D hierarchical porous graphene and combine with conductive polyaniline is an effective way to realize high energy density and good cycling stability. The interlamellar macroporous structure of 3D graphene was constructed by polystyrene (PS) microspheres and nickel foam as double templates. The mesoporous structure was etched in 3D macroporous graphene sheets by potassium hydroxide (KOH) chemical activation. And 3D hierarchical porous graphene (3D-hpGr) composited with polyaniline (PANI) by in situ chemical oxidative polymerization to obtain 3D-hpGr/PANI composites. The effect of the introduction of 3D-hpGr on microstructure, morphology and electrochemical performance of the composites was investigated. PANI nanowire arrays successfully decorate the surface of the 3D-hpGr sheets when the amount of 3D-hpGr reaches 40% (wt%). The specific capacitance of 3D-hpGr/PANI40 reaches 573 F g^-1 at 0.5 A g^-1, much higher than that of pure PANI (419 F g^-1). The retention ratio of 3D-hpGr/PANI40 retains 84% of its initial specific capacitance after 1000 cycles at 1.0 A g^-1, and the cycling stability of all composites is higher than that of pure PANI (69%). The potential drop of 3D-hpGr/PANI composites decreases from 0.339 V to 0.139 V, and the energy density increases consequently. The energy density of 3D-hpGr/PANI40 reaches 31.2 W h kg^-1 at the power density of 0.709 kW kg^-1.