Highly flexible cellulose-based hydrogel electrolytes: preparation and application in quasi solid-state supercapacitors with high specific capacitance

Cellulose has received extensive attention as hydrogel electrolytes in energy storage fields, due to its renewable and environmentally friendly properties. However, it is still difficult to prepare cellulose-based hydrogel electrolytes for supercapacitors with high flexibility, high specific capacitance, and good temperature resistance. Herein, a series of cellulose-based hydrogel electrolytes with good mechanical properties were prepared successfully by incorporating with a small amount of acrylamide/N, N′-methylene bisacrylamide via a simple one-pot strategy and, successively, the resultant hydrogel electrolytes were assembled with the commercial activated carbon, as electrode materials, yielding quasi solid-state symmetric supercapacitors. It was found that the optimum hydrogel electrolytes prepared with 15 wt.% acrylamide/N, N′-methylene bisacrylamide possessed the tensile strength and break elongation as high as 18.7 kPa and 743.3%, respectively. The supercapacitors originating from the above electrolytes showed the excellent electrochemical performance. The specific capacitance could achieve 163.7 F g−1 at 1.0 A g−1 and the corresponding capacitance retention was 87.9% after the constant charge–discharge cycles for 8000 times. Moreover, the supercapacitors could be operated at various bending angles (0°– 180°) and low temperature (− 30 °C) without significant loss of capacitance. These results indicate that the cellulose-based hydrogel electrolytes presented here would have great potential in the application of flexible energy storage devices.