Boosting Performance of Quasi‐Solid‐State Zinc Ion Batteries via Zincophilic Solubilization

Abstract Hydrogel electrolytes hold great promise in tackling severe issues facing aqueous zinc‐ion batteries (AZIBs). However, to satisfy the quest of flexible and eco‐friendly batteries, developing low‐cost and high mechanical durability hydrogel electrolyte remains a challenge. Here, employing the zincophilic solubilizer urea, we break the classical concentration limits of the low‐cost Zn(Ac) 2 salt and introduce it into the hydrogel skeleton. The “salting out” effect give the polymer chain sediments a tighter bundle and twist effect. The as‐formed hydrogel electrolyte can endure 557% high elongation and 3.7 MPa compressive strength to resist repeated zinc plating/striping process and external physical stimuli. The in situ polyurea solid electrolyte interphase (SEI) layer leads to thermodynamically stable anode/electrolyte interface. Utilizing the hydrogel electrolyte, the zinc anode shows high reversibility, leading to an average Coulombic efficiency (CE) of 99.93% for 150 cycles on the Zn//Cu battery. When assembled with NH 4 V 4 O 10 cathode (NVO), the full battery delivers a high capacity of 253.8 mAh g −1 beyond 1000 cycles longevity at 1 A g −1 . The pouch battery also shows a high capacity of 280.7 mAh g −1 at 500 mA g −1 and operate steadily for 90.13% retention after 200 cycles, and maintained a stable voltage even experienced bending and folding.