Polysaccharide-based hydrogels and additives in electrolyte engineering for Zn-ion batteries: anode stabilization...

Aqueous Zn-ion batteries (ZIBs), characterized by intrinsic safety, biocompatibility, and competitive energy density, represent an exceptionally compelling technology for grid-scale energy storage. However, the uncontrollable hydrogen evolution reaction, corrosion, and undesirable dendrite growth triggered by the aqueous electrolytes hamper the further development of ZIBs. In recent years, polysaccharide materials such as cellulose, chitosan, alginates, and cyclodextrins have been widely adopted as electrolyte components in the construction of advanced ZIBs, because of their intrinsically excellent hydrophilicity, environmental friendliness, renewable and abundant production, sufficient active groups, and strong mechanical stability. This review presents a comprehensive summary of the fundamental structures, preparation methods, and comprehensive properties of polysaccharide-based electrolytes. Aqueous ZIBs featuring polysaccharide-based hydrogels are highlighted for their versatile flexibility, high ionic conductivity, and strong adaptability to harsh temperature conditions. To address the active water-derived issues, polysaccharide additives are used to regulate the solvation structures of Zn²⁺ ions and stabilize the anode/electrolyte interface chemistry. Finally, the performance metrics of these strategies are summarized, and the challenges and future perspectives are discussed.