High Energy Density Micro-Supercapacitor Based on a Three-Dimensional Bicontinuous Porous Carbon with Interconnected Hierarchical Pores

On-chip micro-supercapacitors (MSCs) have attracted great attention recently. However, the performance of MSCs is usually unsatisfactory because of the unreasonable pore structure. The construction of a three-dimensional (3D) interconnected porous carbon-based MSC by controllable activation is proposed. The porous monolithic carbon microelectrode activated by ZnO nanowires provides electron/ion bicontinuous conduction path. The fabricated MSC with this microelectrode rendered a high areal specific capacitance of 10.01 mF cm–2, 6 times higher than that of pure pyrolyzed carbon-based MSC, 1.6–5 times higher than that of the MSC with porous carbon activated by ZnO nanoparticles because of its cross-linking macropore–mesopore–micropore structure and considerable areal atomic ratio. The optimization mechanism of the hierarchical channel pore for the electrochemical performance of MSCs is investigated in detail. Four kinds of electrolytes, including H2SO4, redox additive KI/H2SO4, LiCl, and LiTFSi, are employed for constructing MSCs. The voltage window of water in a salt electrolyte assembled LiTFSi-MSC is expanded to 2.5 V. The energy density of LiTFSi-MSC is 6 times higher than that of H2SO4-MSC, which can drive light-emitting diodes without serial or parallel connection. This high-performance 3D interconnected porous carbon-based MSC shows a great potential in applications for large-scale integration of micro-/nanodevices.