Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high energy density supercapacitors

A variety of NiCo2O4 nanostrucutures ranging from nanowire to nanoplate and branched structures were successfully prepared via a simple hydrothermal process. The experimental results show that NiCo2O4 with branched structures possesses the best overall electrochemical performance. The improvement of energy density was explored in terms of hierarchically three-dimensional（3D） metal substrates and a high specific area capacitance, and area energy density is obtained with hierarchically porous Ni monolith synthesized through a controlled combustion procedure.