Hygroscopic and Malleable Dough‐Type Zn–Air Battery in a Dry Condition Utilizing Deliquescence

Abstract Flexible and rechargeable Zn–air batteries (ZAB) are promising candidates for attaining the high energy density required for next‐generation energy storage devices given their half‐open cathode configuration. However, the poor interfacial contact between the immobilized solid‐state electrolyte and porous cathode, and drying‐out of water in the electrolyte at low relative humidity (RH) of 30% or less, cause low performance and short lifespan. Herein, a novel hygroscopic dough‐type electrolyte with water‐absorbing and malleable free‐standing configuration originating from deliquescent KOH and severe gelation of sodium alginate (SA) by facile kneading is proposed. Because appropriate contents are required to absorb water from the atmosphere and obtain the manageable form of the dough used here, the materials composing the dough electrolyte, i.e., SA, water, and KOH, are precisely controlled to ensure high malleability, scalability, ionic conductivity, and good water retention capabilities. The optimized dough inhibits evaporation at low RH and lowers the interfacial resistance with the cathode via tight adhesion. The dough‐type ZABs show noteworthy maximum power density of 160 mW cm −2 with low catalyst mass loading (0.4 mg cm −2 ), specific capacity of 632 mAh g Zn −1 , and stability for 60 h at RH 30% and 120 h even at low temperature of −20 °C, producing reasonable output.