All-in-one and bipolar-membrane-free acid-alkaline hydrogel electrolytes for flexible high-voltage Zn-air batteries

The low operating voltage of 1.4 V limits the widespread application of flexible Zn-air batteries (ZABs) in wearable electronics. However, a high-voltage flexible ZAB has not been achieved yet, which results from the few choices of fitted flexible electrolytes. Now we propose a novel, universal, and simple strategy to design all-in-one and membrane-free acid-alkaline flexible electrolytes based on thermo-reversible Pluronic® F127 hydrogels. Benefiting from the unique sol–gel transition property of Pluronic® F127 hydrogel, the acid and alkaline can be decoupled but integrated simultaneously in one hydrogel. Surprisingly, the as-developed ZAB achieves an unprecedentedly high voltage of 2 V, surpassing all the existing flexible ZABs. Meanwhile, this battery exhibits remarkable high-voltage stability of 37 h and a large area capacity of 1.35 mAh cm⁻² without the use of costly bipolar membranes. Our work presents a pioneering example for flexible high-voltage ZAB and may further inspire other designs of flexible high-voltage aqueous batteries and decoupled dual-electrolyte batteries.