A Hydrogel Electrolyte‐Based Zn−CO 2 Battery with Improved Life

Abstract Environmental‐friendly aqueous Zn−CO 2 batteries present bifunctional potentials of achieving carbon neutrality and energy storage. Nonetheless, anode corrosions derived from H 2 O molecules and high risks of volatilization and leakage hinder the advancement of Zn−CO 2 batteries. In this work, polyvinyl alcohol (PVA)‐based hydrogel electrolyte with fast ion diffusion kinetics, high mechanical strength, and flexibility is developed to replace liquid electrolyte. Since hydroxyl radicals in the polymer chain can interact with H 2 O and Zn 2+ , electrode corrosion from free H 2 O and active H 2 O around Zn 2+ is significantly inhibited, facilitating the uniform deposition of Zn 2+ cations. The introduction of an ionic liquid plasticizer further enhances the interaction between Zn 2+ and polymer backbone, as well as amorphous extent of the electrolyte. The hydrogel electrolyte possesses adequate self‐healing ability, whose ionic conductivity reaches 7.95 × 10 −3 S cm −1 . The symmetric Zn metal batteries containing the electrolyte remain steady for >2000 h under different current densities. Furthermore, the Zn−CO 2 battery based on Ru nanoparticles cathode and hydrogel electrolyte realizes a discharge capacity of 6028 mAh g −1 and stable cyclicity for 90 times. The reaction path of hydrogel electrolyte‐based Zn−CO 2 battery is that CO 2 is reduced to ZnCO 3 and C species followed by reversible decomposition of discharge products on recharge.