Self-supporting electrodes with in situ built aniline on carbon fibers and reduced graphene oxide covalently for stable flexible supercapacitors

Practical applications of flexible electronics have challenged the stability and cycle performance of flexible supercapacitor under continuous mechanical deformation, thus flexible electrode with stable structure has to be considered to maintain high-quality performance. A covalent modification strategy is present here to improve the stability of electrodes. Graphitized carbon cloth (GCC) and reduced graphene oxide (rGO) that modified with aniline by Suzuki reaction, are covalently bonded together with the polymerization of aniline (PANI). The electrode (GCC-PANI-rGO) modified by covalent bonds is stable enough to remain 97.73 % initial specific capacitance after charge-discharge 15,000 times at 40 mA/cm2. The capacitance retention of asymmetric flexible solid supercapacitor (FSSC) prepared by GCC-PANI-rGO and GCC is 108.78 % after 10,000 times mechanical folding. The electrode formed a π-π conjugation system through Suzuki reaction possesses low charge transfer resistance (0.428 Ω), and exhibits high specific capacitance and energy density that up to 11.825 F/cm2 and 1.642 mWh/cm2 at 1 mA/cm2. The energy density of FSSC is 0.266 mWh/cm2 at 1 mA/cm2 and surpasses most FSSC based on PANI and graphene. This work gives an essential covalently synthetic strategy for flexible supercapacitor with stable electrochemical performance in application.