All-cellulose-based high-rate performance solid-state supercapacitor enabled by nitrogen doping and porosity tuning

Renewable cellulose-based papers are considered as a good resource for energy storage devices owing to their interlaced microfibrillar structure and high electrolyte absorptivity. Herein, an all-cellulose-based solid-state high-rate supercapacitor assembled with cellulose paper-derived self-supporting porous carbon electrodes and filter paper separator is designed. Benefiting from ingenious surface chemistry and pore structure engineering, the electrodes possess interconnected network structure, hierarchical pores, and appropriate N/O doping levels. The electrode demonstrates high specific capacitance (222.2 F g(-1) at 0.2 A g(-1)), prominent rate capability (120.1 F g(-1) at 100 A g(-1)), and outstanding cyclic stability (98.7 % capacitance retention after 20,000 cycles at 80 A g(-1)), which surpass most of cellulose-based self-supporting carbon electrodes ever reported. By integrating the well-designed electrodes with a piece of filter paper separator, the assembled symmetric solid-state super -capacitor (1.2 V) achieves an encouraging specific capacitance of 115.0 F g(-1) along with an impressive energy density of 22.9 Wh kg(-1) and a maximum power density of 15.9 kW kg(-1). Moreover, the symmetric super -capacitor with 1 M Et4NBF4 organic electrolyte (3 V) delivered a maximum energy density and power density of 62.5 Wh kg(-1) and 54.9 kW kg(-1), respectively. This study proposes a design concept of all-cellulose-based solid-state supercapacitors, which presents a promising direction toward environmentally friendly and sustainable energy storage technology.