Flexible Zinc–Air Batteries with Ampere-Hour Capacities and Wide-Temperature Adaptabilities

Abstract

Flexible Zn–air batteries (FZABs) have significant potentials as efficient energy storage devices for wearable electronics because of their safeties and high energy-to-cost ratios. However, their application is limited by their short cycle lives, low discharge capacities per cycle, and high charge/discharge polarizations. Accordingly, herein, a poly(sodium acrylate)–polyvinyl alcohol (PANa–PVA)–ionic liquid (IL) hydrogel (PANa–PVA–IL) is prepared using a hygroscopic IL, 1-ethyl-3-methylimidazolium chloride, as an additive for twin-chain PANa–PVA. PANa–PVA–IL exhibits a high conductivity of 306.9 mS cm−1 and a water uptake of 2515 wt% at room temperature. Moreover, a low-cost bifunctional catalyst, namely, Co9S8 nanoparticles anchored on N- and S-co-doped activated carbon black pearls 2000 (Co9S8-NSABP), is synthesized, which demonstrates a low O2 reversibility potential gap of 0.629 V. FZABs based on PANa–PVA–IL and Co9S8-NSABP demonstrate high discharge capacities of 1.67 mAh cm−2 per cycle and long cycle lives of 330 h. Large-scale flexible rechargeable Zn–air pouch cells exhibit total capacities of 1.03 Ah and energy densities of 246 Wh kgcell−1. This study provides new information about hydrogels with high ionic conductivities and water uptakes and should facilitate the application of FZABs in wearable electronics.