A Rechargeable Zn–Air Battery with High Energy Efficiency and Long Life Enabled by a Highly Water‐Retentive Gel Electrolyte with Reaction Modifier

Abstract

Tremendous effort have recently been made in optimizing the air catalysts of flexible zinc–air batteries (ZABs). Unfortunately, the bottleneck factors in electrolytes that largely limit the working life and energy efficiency of ZABs have long been relatively neglected. Herein, an alkaline gel polymer electrolyte (GPE) is fabricated through multiple crosslinking reactions among poly(vinyl alcohol) (PVA), poly(acrylic acid), and graphene oxide followed by intense uptake of an alkali and the KI reaction modifier. The prepared GPE exhibits essentially improved properties compared to traditional PVA gel electrolyte in terms of mechanical strength, ionic conductivity, and water retention capability. In addition, the introduced reaction modifier I− in the GPE changes the path of the conventional oxygen evolution reaction, leading to a more thermodynamically favorable path. The optimized GPE enables flexible ZABs exhibiting an exceptionally low charge potential of 1.69 V, a long cycling time of 200 h, a high energy efficiency of 73%, and rugged reliability under different extreme working conditions. Moreover, the successful integration of ZABs in a variety of real wearable electronic devices demonstrates their excellent practicability as flexible power sources.

A Review of the Use of GPEs in Zinc-Based Batteries. A Step Closer to Wearable Electronic Gadgets and Smart Textiles

“…Notably, the zinc-air battery with the PBE membrane showed the electrochemical rechargeability over 2500 min (at 20 mAcm −2 and 10 min cycle period), compared to the cell with the Celgard3501 (900 min). Song et al [151] fabricated a PVA, PAA, and graphene oxide (GO) co-crosslinked alkaline GPE, named PVAA-GO. Their approach is a holistic one toward the design of a ZAB.…”

Carbon‐based materials for all‐solid‐state zinc–air batteries

“…Zhang et al 86 functionalized the nanocellulose/GO membrane with quaternary ammonium groups and achieved higher ionic conductivity (i.e., hydroxide conductivity is 58.8 mS/cm at 70°C) (Figure 6A). Song et al 87 reported a PVA, PAA, and GO co‐cross‐linked alkaline gel polymer electrolyte containing the KI additive (Figure 6B). The introduction of GO decreased the crystallinity of PVA and the hydrogel connected through PVAA−GO network was more advantageous in water retention and alkali uptake.…”

Flexible and Wearable Power Sources for Next‐Generation Wearable Electronics

“…[132] Present studies focus on addressing these issues to improve the battery lifetime by utilizing novel electrolyte systems. As for the polymer electrolyte materials, various approaches have been proposed including modification of polymer matrices, [133][134][135][136][137] utilization of electrolyte additives, [138,139] exploration of novel ion-conductors, [140] tuning the electrolyte alkalinity, [141,142] and using a carbon dioxide tolerant anion exchange membrane, [143] etc. Excitingly, a crosslinked PVA-PAA-based GPE accompanied with graphene oxide and KI was proposed for flexible ZnÀ air battery, in which the introduced reaction modifier I À could change the conventional path of OER and GO prolonged the diffusion distance to release water from the polymer matrix.…”

“…Excitingly, a crosslinked PVA-PAA-based GPE accompanied with graphene oxide and KI was proposed for flexible ZnÀ air battery, in which the introduced reaction modifier I À could change the conventional path of OER and GO prolonged the diffusion distance to release water from the polymer matrix. The resultant battery showed an exceptionally low charge potential of 1.69 V with a long cycling time of 200 h. [137] Although the obtained cycle life of flexible metalÀ air batteries still falls far behind the requirement in practical applications, every effort reaps the rewards to reach the target of daily use. Besides, the encapsulation of flexible metalÀ air batteries shows promising potential to tackle the challenges of their half-open architectures.…”