Lignin-Inspired Hydrogel Matrixes with Adhesion and Toughness for All-Hydrogel Supercapacitors

Flexible supercapacitors are promising energy storage devices for their portability and long cycle life. However, the weak interfacial adhesion between contiguous layers of flexible supercapacitors limits their practical applications. Here, a hydrogel matrix by integrating Ag-Lignin nanoparticles into polyacrylamide network is reported. Due to the unique interwoven-microfibrils structure and non-covalent interactions, the obtained hydrogel matrix shows strong adhesion and toughness. The assembled all-hydrogel supercapacitor based on the hydrogel matrix has robust interfaces and shows high specific capacitance (298.6 F g -1 at 10 mV s -1 ), outstanding rate performance, a high energy density of 13.7 Wh kg -1 at the power density of 201.4 W kg -1 and 91.9% capacitance retention after 5000 cycles. Remarkably, the all-polymer device shows superior capacitance retention after mechanical deformations of 5000 cycles without slippage between contiguous layers. This study proposes a commendably effective approach to improve the interfacial adhesion in integrated supercapacitors and extends the application range of flexible supercapacitors.