Inorganic nanoparticle-enhanced double-network hydrogel electrolytes for supercapacitor with superior low-temperature adaptability

In the context of the ongoing evolution within supercapacitor technology, heightened scholarly focus has been directed towards incorporating biomass materials in hydrogel electrolytes. Lignin, a polyphenolic polymer with pronounced aromatic and oxygen-functional moieties, is sparingly employed in isolation as a hydrogel matrix owing to its inherent mechanical deficiencies. Here, double-network hydrogels are prepared by copolymerizing lignin and sodium acrylate (AM). Integrating SiO2 inorganic nanoparticles augments the resultant double-network hydrogels' structural robustness and performance attributes. The supercapacitor, fabricated using the optimized hydrogel electrolyte, demonstrates a notable ionic conductivity of 0.096 S cm−1, accompanied by exemplary flexibility and resistance to freezing. The refined flexible supercapacitor manifests a considerable specific capacitance of 150 F g−1 at −30 °C, representing approximately 80 % of its efficacy at room temperature. This multifaceted hydrogel polymer electrolyte, exhibiting commendable electrochemical properties, holds promise for diverse supercapacitor applications across varied environmental conditions. Anticipation arises that this efficacious strategy may furnish a novel conceptual framework and avenue for utilizing lignin in high-performance energy storage devices.