A cellulose-based interpenetrating network hydrogel electrolyte for flexible solid-state supercapacitors

Solid flexible electrolyte plays important roles in flexible supercapacitors. However, their low ionic conductivity and mechanical stability restrict their applications. Therefore, the development of flexible solid electrolytes with excellent mechanical properties and electrochemical performance is highly desirable. In this work, a cellulose-polyacrylamide double network hydrogel electrolyte was prepared by a simple method, with cellulose as the first network layer and polyacrylamide as the second network layer. The ionic conductivity of the resulting material reached 131.4 mS cm−1. The dual network endowed the hydrogel electrolyte with abundant ion channels and excellent mechanical stability, effectively reducing the interfacial contact resistance with the electrode. The activated carbon-based supercapacitor with cellulose-Polyacrylamide interpenetrating network hydrogel electrolyte delivered high specific capacitance of 989 mF cm−2 at 2 mA cm−2. Besides, the electrochemical behavior of the supercapacitor showed no obvious differences from supercapacitors assembled with aqueous electrolytes. The excellent adhesion and flexibility of hydrogels allowed the supercapacitors to cope with deformation and compression at various angles while maintaining stable electrochemical behavior. In summary, the proposed approach is promising for the development of flexible energy storage devices with good electrochemical and mechanical stability.