Starch‐Based Superabsorbent Hydrogel with High Electrolyte Retention Capability and Synergistic Interface Engineering for Long‐Lifespan Flexible Zinc−Air Batteries

Abstract

The advent of wearable electronics has strongly stimulated advanced research into the exploration of flexible zincÀ air batteries (ZABs) with high theoretical energy density, high inherent safety, and low cost. However, the half-open battery structure and the high concentration of alkaline aqueous environment pose great challenges on the electrolyte retention capability and the zinc anode stability. Herein, a starchbased superabsorbent hydrogel polymer electrolyte (SSHPE) with high ionic conductivity, electrolyte absorption and retention capabilities, strong alkaline resistance and high zinc anode stability has been designed and applied in ZABs. Experimental and calculational analyses probe into the root of the superiority of SSHPEs, confirming the significance of the carboxyl functional groups along their polymer chains. These features endow the as-fabricated ZAB a long cycle life of 300 h, much longer than that with commonly used poly(vinyl alcohol)-based electrolyte.

Sustainable zinc–air battery chemistry: advances, challenges and prospects

“…GPEs with desirable mechanical robustness, high ionic conductivity, and excellent compatibility with electrodes are critical for flexible ZABs. 288 Hydrogels are polymeric materials with 3D network structures, consisting of crosslinked polymer chains and inner aqueous electrolytes. The highly interconnected network of the polymer matrix provides enough space to lock the electrolyte and the unblocked pathways for ion diffusion.…”

Preparation of PVA/cellulose composite hydrogel electrolytes based on zinc chloride-dissolved cellulose for flexible solid-state capacitors

“…However, it is worth noting that such methods not only entail complex preparation processes but also require further evaluation of the environmental impact of the introduced organic solvents and ionic liquids. 19–22…”

Extending the Cycle Lifetime of Solid-State Zinc-Air Batteries by Arranging Stable Zinc Species Channels

“…To date, the polymer hydrogels decorated with abundant hydrophilic groups, including poly­(vinyl alcohol) (PVA), poly­(acrylic acid) (PAA), polyacrylamide (PAM), and their derivatives, have been widely reported as solid-state electrolytes in ZABs. The hydrogels are always encounter water loss and deformation due to the semiopen structure of ZABs. ,− An interpenetrated network can improve the mechanical strength of hydrogels and also reduce the size shrinkage. , In addition, some reports have adopted the strategy of creating dense hydrogen bond networks, such as by adding polysaccharides, to promote the desolvation of hydrated zinc species during the charging process of ZABs. − Meanwhile, other reports adopt decorating hydrogels with the cationic groups to construct channels for transferring OH – ions and also expect to alleviate the alkaline corrosion . However, there is still lack of understanding the transfer pathway of zinc species in hydrogels, although several mechanisms have been proposed to explain the OH – channels. − It is difficult to distinguish the individual contribution of zinc species from the apparent ion conductivity due to the presence of complex solvated zinc species in hydrogels.…”