A Hydrogel Electrolyte-Based Zn−CO2 Battery with Improved Life

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.