Lignin-induced rapid-synthesis of deep eutectic solvent-based gel with high robustness and conductivity applied for flexible quasi-solid-state supercapacitors

A novel rapid-synthesis method for the preparation of high-performance deep eutectic solvent (DES)-based gel was proposed for constructing flexible quasi-solid-state supercapacitors. The dynamic redox reaction between silver ions and lignin produced large amounts of free radicals, which triggered the polymerization of acrylic acid monomer (AA) to form silver-lignin nanoparticle/DES/Poly (acrylic acid) (Ag-L NPs/DES/PAA) composite gel. Ag-L NPs constructed a dynamic redox system that generated catechol groups, triggering rapid self-gelation of Ag-L NPs/DES/PAA at room temperature, while imparting long-term and repeatable adhesion ability to the hydrogel. In addition, DES, as the liquid component of Ag-L NPs/DES/PAA, not only provided a good solution system for lignin but also enhanced its electrochemical performance and stability. Thanks to the synergistic effects of DES and the dynamic transformation of lignin and silver, Ag-L NPs/DES/PAA not only exhibited a high conductivity of over 10 mS/cm, but also showed a remarkable adhesion strength of over 80 KPa. Moreover, the presence of lignin endowed Ag-L NPs/DES/PAA with more than 300% strain and over 350 KPa compression performance. A supercapacitor based on this assembly exhibited a high specific capacitance (208F g−1, 0.5 A g−1) and an impressive capacity retention rate of 92.05% after 3000 cycles. This research offered insightful information on the use of lignin in flexible electronics.