CO2 Ionized Poly(vinyl alcohol) Electrolyte for CO2-Tolerant Zn-Air Batteries

CO2 poisoning of alkaline electrolytes is a critical issue that affects the energy efficiency and lifespan of Zn-air batteries. However, few strategies have been explored to address this issue because it is challenging to block CO2 from the outer atmosphere. Herein, a CO2-tolerant flexible quasi-solid-state electrolyte for Zn-air batteries, which is achieved by the pre-fixation of CO2 on poly(vinyl alcohol) (PVA) via its ionization in the form of side -OCO2- groups (PVA-TMG), is reported. The pre-fixation of CO2 enables excellent CO2 tolerance and alleviates the Zn dendrite and ZnO deposition, because the -OCO2- groups can strongly interact with the Zn2+. In addition, PVA-TMG exhibits higher ionic conductivity and better water retention capability than the pristine PVA. Consequently, the fabricated Zn-air batteries deliver excellent performance in both air and a CO2-rich atmosphere. The optimized PVA-TMG presents a cycling lifetime 12 times longer than that of the pristine PVA in the atmosphere with 22.7 vol% CO2. The feasible study presented here presents a new milestone in CO2 utilization with energy storage technology.