Reconstructing hydrogen bond network with chaotropic salt enables low-temperature and long-life nickel-zinc batteries

Aqueous nickel-zinc (Ni–Zn) batteries have attracted wide attention due to their high energy density, high safety and low cost. However, the inferior cycling stability due to side reactions and the poor low-temperature electrochemical performance of aqueous electrolyte limit the large-scale application of Ni–Zn batteries. Herein, a nickel-cobalt-based metal-organic framework (NiCo-MOF) cathode is synthesized, which improves the cycling stability and rate performance of Ni–Zn batteries. Furthermore, a stable inorganic electrolyte with a freezing point lower than −112 °C by introducing NaClO4 chaotropic salt additive into alkaline electrolyte is constructed. Benefiting from the reconstructing effect of ClO4‐ on the water hydrogen bond network, the electrochemical stability window is widened from 1.56 V to 2.06 V, both oxygen evolution reaction (OER) on cathode and zinc corrosion on anode are inhibited. The batteries assembled with zinc foil as anode, NiCo-MOF as cathode (Zn||NiCo-MOF) and 4 M NaOH + 3 M NaClO4 electrolyte provides a capacity of 96.5 mAh/g at 2 mA/cm2 at −40 °C, corresponding to an 85.2 % capacity retention of that at 25 °C. In addition, the batteries operate stably at 5 mA/cm2 for 7500 cycles with a specific capacity retention of 92.0 % at −40 °C.