Hygroscopic Double‐Layer Gel Polymer Electrolyte toward High‐Performance Low‐Temperature Zinc Hybrid Batteries

Abstract Aqueous zinc hybrid batteries have been rapidly developed to overcome the sluggish kinetics of divalent zinc ions in the cathode of Zn‐based batteries. However, their cycle life is limited by water decomposition during the operation, specifically at low current rate for long‐term cycles. Herein, we propose a zinc hybrid battery with excellent adaptability of low‐temperature, at which the water decomposition is seriously restrained. The battery involves a hygroscopic double‐layer gel polymer electrolyte, in which one layer close to the LiFePO 4 cathode provides Li + , and the other layer close to the Zn anode provides Zn 2+ . The use of the double‐layer electrolyte can both weaken the water reactivity and increase the salt concentration, leading to a high‐performance of the batteries. It enables the hybrid batteries to operate at −20 °C and achieve stability for over 300 cycles with a capacity retention of 85.14 % and Coulombic efficiency of ∼100 % at a low current rate of 85 mA g −1 . Moreover, the spontaneous hygroscopic system, opposite to that of “water‐in‐salt”, can efficiently reduce manufacturing costs and improve ionic conductivity. This provides an advanced pathway for designing electrolytes to achieve high‐performance and low‐cost batteries with excellent adaptability of low‐temperature.