A self-healing zinc ion battery under -20 °C

Self-healable aqueous batteries can improve their service lifetime and solve safety issues induced by device failure during large deformations at room temperature. At low temperatures (e.g. -20 °C), they generally lose most of their electrochemical performance and self-healing function since water molecules in aqueous electrolytes are inevitably frozen. Herein, a simple and effective method is adopted to prepare an anti-freezing and self-healable polyelectrolyte (AF-SH[sbnd]CPAM) by the in-situ polymerization of acrylamide monomer in a water/ethylene glycol solution. In AF-SH[sbnd]CPAM, ethylene glycol simultaneously achieves the anti-freezing and self-healing performance of the polyelectrolyte by restraining the icing of water molecules and dynamically adjusting the molecular interactions between polymer chains and water. Based on this polyelectrolyte, a self-healable zinc ion battery working at -20 °C is fabricated for the first time by using the gold-sprayed carbon nanotube/polyaniline film as cathode and the zinc foil as anode. This battery can deliver a high specific capacity of 233.9 mAh g ^{− 1} at room temperature, exceeding that of those reported aqueous Zn/polyaniline batteries. More impressively, it also shows the prominent self-healablity with a high capacity retention of 90.4% after three cutting/self-healing cycles at -20 °C, presenting a breakthrough in low-temperature self-healing function of aqueous batteries.