Biopolymer electrolytes and composites based on chitosan for electrochemical processes: developing technologies,...

Chitosan, a biopolymer with multifunctionality that occurs naturally from chitin, was found to be an efficacious high-potential platform for building green polymer electrolytes and electrochemical device composite materials. Its inherent properties like dense functional groups, biocompatibility, film-forming nature, and ease of chemical modification, favorably position it as a reliable substitute for conventional synthetic polymers. This review encompasses chitosan-based biopolymer electrolytes and composites, the mechanism of ionic conductance, structural tuning, and their incorporation into high-performance electrochemical devices. The review places particular importance on recent strategies pursued for enhancing ionic conductivity, mechanical stability, and electrochemical performance by chemical functionalization, blending, and nanomaterial inclusion. Particular focus is placed on ion dynamic awareness, proton and cation conducting channels, and polymer-filler interaction for charge transportation optimization. Application domains of fuel cell, battery, supercapacitor, and bioelectronic devices are comprehensively discussed with focus placed on both the achievements and ongoing challenges of chitosan systems. Finally, the review challenges issues of durability, scalability, and sustainability and outlines directions for future material engineering and technology integration. Bridging the gap between fundamental knowledge and real-world applications, this review article serves to illustrate the potential of chitosan-based electrolytes and composites to propel next-generation green and high-performance electrochemical technologies.