Reliable and flexible supercapacitors toward wide-temperature operation based on self-supporting SiC/CNT composite films

Abstract

To date, many efforts have been made in exploring flexible supercapacitors (SCs) to meet the balance between electrochemical and mechanical performance, which is currently still a grand challenge. In this study, we report the rationally designed editable and flexible electrode composed of SiC nanowires and carbon nanotubes (SiC/CNTs), which couples the excellent mechanical properties of SiC nanowires and the high conductivity of CNTs. The specific capacitance of such a self-supporting electrode could be up to 8.43 F g⁻¹ at a current density of 0.02 A g⁻¹, which is more than 4 times that of the pure SiC analogue (i.e., 1.77 F g⁻¹). The soft-packaged SCs deliver high flexibility, as well as robust mechanical and electrochemical properties, which could be well maintained with nearly no change in the structure and performance against various bending angles. Additionally, the flexible SCs are robust for wide-temperature operation from −30 °C to 50 °C, with capacitance retentions of 89.3% and 95.0% over 10 000 cycles at 50 °C and −30 °C, respectively. Moreover, they have long-term cycle stability for up to 14 000 cycles under progressively varied temperatures between −30 and 50 °C, presenting their promising applications as reliable energy storage devices that can operate under wide-temperature harsh conditions.