Monodentate\nAcetate Anion Enhanced Hydrogel Electrolyte\nfor Long-Term Lifespan Zn-Air Batteries

Flexible\nZn-air batteries (FZABs) hold significant promise in diverse\napplication scenarios with high safety and compatibility yet are still\nimpeded by byproduct formation and poor water retention. Here, the\nneutral hydrogel electrolyte GAHE is engineered by <i>in situ</i> polymerizing acrylamide (AM) in a solution composed of cationic\nguar gum (CGG) and acetate salts to conquer the above challenges.\nThe acetate anions (OAc<sup>–</sup>) exert a pH near 7 to effectively\ninhibit the side reactions triggered by H<sup>+</sup>. Meanwhile,\nthe monodentate OAc<sup>–</sup> ions in LiOAc have fast ion\ndiffusion kinetics and form hydrogen bonds between the released carbonyl\ngroups and H<sub>2</sub>O to further suppress water activity for great\nside reaction prevention and water retention. Additionally, the <i>in situ</i> polymerization strategy realizes a polymer with\nhigh mechanical properties and great electrochemical interfacial stability\nand further improves the water retention property with hydrophilic\ngroups. Consequently, GAHE gives the FZABs a lifespan of 2050 h at\nroom temperature and 2940 h at −35 °C. This work provides\nconcepts for electrolyte design for water retention and side reaction\ninhibition properties of aqueous devices.