Abstract
Biodegradable gel-polymer electrolytes (GPEs) represent a promising alternative to liquid electrolytes and synthetic separators in solid-state supercapacitors for wearable electronics, biomedical devices, and autonomous sensors. They offer enhanced safety, prevent electrolyte leakage, increase device flexibility, and reduce environmental impact. This review systematizes current approaches to the development of biodegradable GPEs based on chitosan, alginate, gelatin, cellulose and its derivatives, starch, lignin, polylactic acid, and other polymers. Methods of modification (crosslinking, functionalization, compositing, incorporation of nanofillers) and mechanisms of ion transport in gel matrices are considered. Particular attention is paid to the influence of the electrolyte on ionic conductivity, equivalent series resistance (ESR), operating voltage, and cyclic stability. The main limitations of biodegradable GPEs and prospects for the development of “green solid-state energy storage devices are discussed.