Hierarchical porous graphene film: An ideal material for laser-carving fabrication of flexible micro-supercapacitors with high specific capacitance

Based on a novel hierarchical porous reduced-graphene-oxide (RGO) film, all-solid-state flexible micro-supercapacitors (MSCs) with the high performances are fabricated through a one-step laser-carving approach. The macro/mesoporous RGO film, which is desirable for the ion transport and diffusion to be used as the electrode, was prepared from graphene oxide (GO) hydrogel by blade-casting and chemical reduction. The porous RGO film after mechanical compression was patterned to give interdigitated electrodes by irradiation with a picosecond laser. The results showed that the as-prepared in-plane MSCs exhibit a high areal specific capacitance of 37.95 mF cm−2 at a current density of 0.6 mA cm−2, and 36.38 mF cm−2 at a scan rate of 10 mV s−1, both of which are higher than most of the reported values for all-solid-state MSCs based on carbon materials. Meanwhile, the MSCs possess superior rate capability, good mechanical stability, excellent flexibility and long cycle life. For applications, the MSCs can be easily connected in series, parallel, or combined series and parallel to output high voltage and energy.