Densely packed graphene nanomesh-carbon nanotube hybrid film for ultra-high volumetric performance supercapacitors

For the first time, we report a novel strategy to prepare densely packed graphene nanomesh-carbon nanotube hybrid film (GNCN) through a simple graphene etching process and subsequent vacuum-assisted filtration method. The ion diffusion ability of the GNCN film is greatly enhanced due to the contribution of cross-plane diffusion from graphene nanomesh and in-plane diffusion from CNT-graphene sandwiched structure. In addition, carbon nanotubes can also efficiently improve the overall electrical and mechanical properties of the hybrid film. Based on its high surface area, fast ion diffusion and high film density, the GNCN film electrode exhibits a specific capacitance of 294Fg−1 at 5mVs−1, higher than the RGO film (185Fg−1), as well as excellent rate capability and outstanding cycling performance (93% capacitance retention after 5000 cycles). It is worth noting that the GNCN film electrode shows high energy density of 26WhL−1, and ultra-high volumetric capacitance of 331Fcm−3. The strategy provides a facile and effective method to achieve high volumetric performance electrode materials for supercapacitor.