Temperature inversion enables superior stability for low-temperature Zn-ion batteries

It is challenging for aqueous Zn-ion batteries (ZIBs) to achieve comparable low-temperature (low-T) performance due to the easy-frozen electrolyte and severe Zn dendrites. Herein, an aqueous electrolyte with a low freezing point and high ionic conductivity is proposed. Combined with molecular dynamics simulation and multi-scale interface analysis (time of flight secondary ion mass spectrometry three-dimensional mapping and in-situ electrochemical impedance spectroscopy method), the temperature independence of the V₂O₅ cathode and Zn anode is observed to be opposite. Surprisingly, dominated by the solvent structure of the designed electrolyte at low temperatures, vanadium dissolution/shuttle is significantly inhibited, and the zinc dendrites caused by this electrochemical crosstalk are greatly relieved, thus showing an abnormal temperature inversion effect. Through the disclosure and improvement of the above phenomena, the designed Zn||V₂O₅ full cell delivers superior low-T performance, maintaining almost 99% capacity retention after 9500 cycles (working more than 2500 h) at −20 °C. This work proposes a kind of electrolyte suitable for low-T ZIBs and reveals the inverse temperature dependence of the Zn anode, which might offer a novel perspective for the investigation of low-T aqueous battery systems.