Quasi-aligned SiC@C nanowire arrays as free-standing electrodes for high-performance micro-supercapacitors

Abstract

Currently, it still remains a grand challenge to enhance energy density of micro-supercapacitors (MSCs) without sacrificing power density, cycle life and other key performance. Herein, we reported the exploration of free-standing electrodes for MSCs based on quasi-aligned SiC nanowire arrays wrapped by ultrathin graphitic carbon film (SiC@C). Such rationally designed SiC@C architecture bring an optimal specific capacitance of 78.98 mF cm−2 at a current density of 0.2 mA cm−2, which was enhanced by more than 700% in comparison to that of pure SiC counterpart (9.56 mF cm−2). The aqueous-based MSCs exhibit a high specific capacitance, fast charge-discharge rate, excellent rate capability, and long-term cycling stability (94.1% capacity retention after 10000 charge-discharge cycles). The ionic-liquid-based MSCs had an extended operating voltage up to 2.6 V with an energy density up to 2.84 μW h cm−2 (at a power density of 65.1 μW cm−2), which was a new record of SiC-based SCs, and superior to most of those of nanowire-based MSCs in other material systems ever reported.