From:  Functional lignin hydrogels for biosensors and biomedical therapy

 The different types of applications of lignin-based hydrogels for energy.

MaterialElectrode material Device typePropertiesApplicationReferences
Lignosulfonate functionalized graphene hydrogel (LSGH) fabricated with H2SO4 polyvinyl alcohol gel electrolyteMetal free flexible LSGH electrodeFlexible supercapacitorSpecific capacitance of 432 Fg–1 in aq. Electrolyte as compared to pure graphene hydrogel (238 Fg–1). Also, exhibit high mechanical stabilityFlexible energy device[156]
Chemical crosslinked lignin hydrogel electrolytesElectrospun lignin/polyacrylamide nanofiber electrodesFlexible supercapacitorHigh capacitance of 129.23 Fg–1. Delivers a maximum energy & power density of 4.49 Wh·kg–1 & 2.63 kW·kg–1 respectivelyEnergy storage devices[157]
Double crosslinked lignin hydrogel electrolytePANI-deposited carbon clothFlexible supercapacitorExhibit high mechanical strength (4.74 MPa) and ionic conductivity (0.088 cm–1)Compression-resistant electronics[158]
GAC-2 nitrogen-doped activated carbon/graphene hydrogel electrodeGraphene oxideFlexible supercapacitorShow high mechanical flexibility & exhibit energy density of 26.9 Wh·kg–1Energy storage electrical devices[159]