A Hydrogel Electrolyte with High Adaptability over a Wide Temperature Range and Mechanical Stress for Long‐Life Flexible Zinc‐Ion Batteries

Abstract Flexible zinc‐ion batteries have garnered significant attention in the realm of wearable technology. However, the instability of hydrogel electrolytes in a wide‐temperature range and uncontrollable side reactions of the Zn electrode have become the main problems for practical applications. Herein, N,N‐dimethylformamide (DMF) to design a binary solvent (H 2 O‐DMF) is introduced and combined it with polyacrylamide (PAM) and ZnSO 4 to synthesize a hydrogel electrolyte (denoted as PZD). The synergistic effect of DMF and PAM not only guides Zn 2+ deposition on Zn(002) crystal plane and isolates H 2 O from the Zn anode, but also breaks the hydrogen bonding network between water to improve the wide‐temperature range stability of hydrogel electrolytes. Consequently, the symmetric cell utilizing PZD can stably cycle over 5600 h at 0.5 mA cm − 2 @0.5 mAh cm −2 . Furthermore, the Zn//PZD//MnO 2 full cell exhibits favorable wide‐temperature range adaptability (for 16000 cycles at 3 A g −1 under 25 °C, 750 cycles with 98 mAh g −1 at 0.1 A g −1 under ‐20 °C) and outstanding mechanical properties (for lighting up the LEDs under conditions of pressure, bending, cutting, and puncture). This work proposes a useful modification for designing a high‐performance hydrogel electrolyte, which provides a reference for investigating the practical flexible aqueous batteries.