LAUSR

Abstract Improving energy density while maintaining power density and cycle stability is the most serious challenge for supercapacitors. The solid active electrode material might possess a higher redox species density compared with its traditional counterpart, however, its electrochemical reaction kinetics is several magnitude orders lower in solids than that in liquids, leading to a deterioration of power density. Thus, a new approach based on 3-TEMPO-1-methylylimidazolium bromide (MIm+-TEMPO• Br−) biredox electrolyte, and a PANI-gel network modified carbon paper (PNcp) electrode for supercapacitor were developed in this study. The biredox electrolyte possesses a high energy density comparable to solid redox materials and a fast kinetics of liquid redox reaction, while the cross-diffusion of ions leads to a serious voltage drop which presents an inherent self-discharge problem. Fortunately, the PNcp prepared by a millisecond photo-thermal process makes up for this shortcoming. On one hand, its unique PANI-gel network structure protects the biredox electrolyte from cross-diffusion phenomenon, on the other hand, the combination of doping/dedoping process of PANI and redox process of MIm+-TEMPO• Br− provides an extra effect to prevent the self-discharge and attain a synergetic electrochemical performance. This method explores an avenue to pursue for battery level energy density meanwhile maintains good power density.