Non-precious bifunctional high entropy alloy catalyst and layered double hydroxide enhanced gel electrolyte based rechargeable flexible zinc-air batteries

Cost-effective highly efficient and stable bifunctional oxygen catalysts are critical for practical applications of rechargeable zinc-air batteries (ZABs). In this study, a non-precious bifunctional FeCoNiCuMo high entropy alloy (HEA) catalyst was developed, exhibiting outstanding dual-functionality toward catalysis of oxygen reduction and oxygen evolution reactions, with an ultralow voltage gap (ΔE10) of 0.67 V. The FeCoNiCuMo HEA based ZAB exhibited a high peak power density of 298 mW cm−2 at a high current density of 412 mA cm−2 and an outstanding cycling stability over 1576 cycles (788 h) at 10 mA cm−2 with a minor voltage gap increase of 6.2 %. Incorporation of CoNi layered double hydroxide nanowire arrays to poly(vinyl alcohol) (PVA) gel electrolytes significantly enhanced the aqueous electrolyte adsorption and water retention capabilities and ionic conductivities of the PVA gel, leading to much improved efficiency and stability of the flexible ZAB (FZAB), with an increase in peak power densities from 72 to 102.9 mW cm−2 and a prolonged lifespan from 35 to 58 h at 5 mA cm−2. The FZAB exhibited excellent mechanical stability, with no variations in voltage gaps observed under increasing bending.