All-solid-state flexible zinc-air battery with polyacrylamide alkaline gel electrolyte

The rapid development of flexible electronic devices prompts the extensive attentions of the all-solid-state flexible zinc-air batteries (ZABs). Nevertheless, the low energy conversion efficiency and output power density hinder the practical application of all-solid-state flexible ZABs due to the lacks of bifunctional oxygen catalysts with high catalytic activity and flexible solid electrolytes with high ionic conductivity. Herein, we report an active and cost-effective oxygen catalyst of manganese dioxide (MnO2) nanowires supported on nitrogen-doped reduced graphene oxide (MnO2/NRGO-Urea) synthesized by a facile one-pot process. Along with superior stability, MnO2/NRGO-Urea shows the prominent activities for oxygen reduction and evolution reactions (ORR and OER), and lowest potential difference between ORR and OER among most of the manganese dioxides reported recently. Importantly, the polyacrylamide (PAM) based alkaline gel electrolyte (AGE) which shows much higher hydroxide-ion conductivity (215.6 mS cm−2) than the state-of-the-art polyvinyl alcohol (PVA)-based AGEs is employed in the all-solid-state flexible ZAB. Thanks to the MnO2/NRGO-Urea catalyst and PAM-based AGE, the maximum power density (Pmax) of the as-fabricated all-solid-state flexible ZAB reaches 105.0 mW cm−2 with extraordinary mechanical flexibility and robustness. Our work offers a cost-effective strategy for all-solid-state flexible ZABs with high power density and excellent energy conversion efficiency.