High-Performance Biomass-Based Flexible Solid-State Supercapacitor Constructed of Pressure-Sensitive Lignin-Based and Cellulose Hydrogels

Employing renewable, earth-abundant, environmentally friendly, low-cost natural materials to design flexible supercapacitors (FSCs) as energy storage devices in wearable/portable electronics represents the global perspective to build sustainable and green society. Chemically stable and flexible cellulose and electroactive lignin have been employed to construct a biomass-based FSC for the first time. The FSC was assembled using lignosulfonate/single-walled carbon nanotube_HNO (Lig/SWCNT_HNO) pressure-sensitive hydrogels as electrodes and cellulose hydrogels as an electrolyte separator. The assembled biomass-based FSC shows high specific capacitance (292 F g^-1 at a current density of 0.5 A g^-1), excellent rate capability, and an outstanding energy density of 17.1 W h kg^-1 at a power density of 324 W kg^-1. Remarkably, the FSC presents outstanding electrochemical stability even suffering 1000 bending cycles. Such excellent flexibility, stability, and electrochemical performance enable the designed biomass-based FSCs as prominent candidates in applications of wearable electronic devices.