Facile fabrication of 2D porous carbon nano-flake electrodes for high-performance flexible on-chip micro-supercapacitors

Graphene has been continuously investigated as electrode material for flexible micro-supercapacitors (MSCs). However, owing to the lack of in-plane ion transport channels and low specific surface area caused by restacking of graphene sheets, its electrochemical performance is unsatisfactory. To solve this problem, herein, we present a novel strategy for preparing 2D porous carbon nano-flake (PCF) through simple chlorine-etching MXene (Ti3C2). Distinctly different from the commonly graphene sheets, the prepared PCF shows high specific surface area (1239 m2 g−1) and abundant ion transport channels in c-axis direction, thus enhancing electrochemical performance. When the prepared PCF is used as the electrode for MSCs, the MSCs behaves excellent electrochemical performances. The areal capacitance and the energy density is up to 102.1 mF cm−2 (at current density of 0.2 mA cm−2) and 13.2 μWh cm−2 (at 0.1 mW cm−2 power density), respectively, which, to the best of our knowledge, are both among the highest values reported for MSCs with the graphene electrodes. In addition, the fabricated MSCs also show excellent mechanical flexibility and easy-adjustment in the voltage and capacitance by connecting multiple MSCs in series and parallel. These results indicate that the prepared PCF has great application potential in micro electrochemical energy storage devices. © 2022 Elsevier Ltd