An Ultralow Temperature Aqueous Battery with Proton Chemistry

Conventional aqueous batteries usually suffer from serious capacity loss under subzero conditions owing to the freeze of electrolytes. To realize the utilization of aqueous batteries in extremely cold climates, low‐temperature aqueous battery systems have to be developed. Herein, an aqueous Pb‐quinone battery based on p‐chloranil/reduced graphene oxide (PCHL‐rGO) in H 2 SO 4 electrolyte is developed. Such aqueous Pb/PCHL‐rGO batteries display H + insertion chemistry, which endows the batteries with fast reaction kinetics and high rate capability. In addition, the hydrogen bonds between water molecules can be significantly damaged in electrolyte by modulating the interaction between SO 4 2− and water molecules, lowering the freezing point of electrolyte. As a result, the Pb/PCHL‐rGO batteries deliver extraordinary electrochemical performance even at −70 °C. This work will broaden the horizons of aqueous batteries and open up new opportunities to construct low‐temperature aqueous batteries.