High-performance supercapacitors based on graphene/MnO2/activated carbon fiber felt composite electrodes in different neutral electrolytes

Abstract

Graphene/MnO₂ composites are introduced into activated carbon fiber felt (ACFF) to fabricate composite textile electrodes. Their micro-structure, electrical properties and electrochemical performance for supercapacitor applications in different neutral electrolytes (1 M NaNO₃ and Ca(NO₃)₂ aqueous solutions) have been studied. The composite electrodes have similar pore features to original ACFF textiles, but show notably enhanced electrical and electrochemical performance. The composite textile electrodes show low electrical resistance, high specific capacitance (up to 1516 mF cm⁻² in neutral electrolytes) and excellent cycling stability (no capacitance decay after 5000 charge–discharge cycles). Besides, electrochemical capacitance of composite textile electrodes in Ca(NO₃)₂ electrolyte is higher than that in NaNO₃ electrolyte at low scan rates (1–5 mV s⁻¹), but the situation is reversed when scan rates are higher than 10 mV s⁻¹. Above all, the results show that our low-cost composite textile electrodes are high-performance in neutral electrolytes, which is helpful for developing large-scale energy storage devices.