A low-temperature aqueous Se-based battery with rapid reaction kinetics and unprecedented energy density

Current strategies to improve the low-temperature performance of aqueous batteries typically comes at the cost of safety, reaction kinetics, or overall energy density. Besides, the existing cathodes of low-temperature aqueous batteries suffer from low specific capacity (typically below 200 mAh g−1). Here, we develop a low-temperature-tolerant selenium-based battery through regulating the coordination anions of charge carrier. The constructed Zn-Se battery delivers an ultrahigh discharge specific capacity of about 1069 mAh gSe−1 and a record-breaking energy density of 1180 Wh kgSe−1 (116 Wh kg(full cell)–1) at −50 °C, surpassing available low-temperature aqueous batteries by a significant margin. Crucially, this approach not only maintains safety but also enhances reaction kinetics (875 mAh gSe−1 at 30 A g−1) and overall energy density. Our results suggest Se cathode undergoes a multi-step conversion reaction: Se↔ CuSe↔ Cu3Se2 ↔ Cu1.8Se ↔ Cu2Se. This work not only sets a new benchmark for low-temperature aqueous batteries but also effectively mitigates the common trade-off linked with traditional antifreeze additives.