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

Abstract

Current strategies to improve the low-temperature performance of aqueous batteries typically come at the cost of safety, reaction kinetics, or overall energy density. Besides, the existing cathodes of low-temperature aqueous batteries suffer from a low specific capacity (typically below 200 mA h g⁻¹). Here, we developed a low-temperature-tolerant selenium-based battery by regulating the coordination anions of charge carriers. The constructed Zn–Se battery delivers an ultrahigh discharge specific capacity of about 1069 mA h g_Se⁻¹ and a record-breaking energy density of 1180 W h kg_Se⁻¹ (116 W h kg_{(full cell)}⁻¹) at −50 °C, surpassing those of available low-temperature aqueous batteries by a significant margin. Crucially, this approach not only maintains safety but also enhances the reaction kinetics (875 mA h g_Se⁻¹ at 30 A g⁻¹) and the overall energy density. Our results suggest that the Se cathode undergoes a multi-step conversion reaction: Se ↔ CuSe ↔ Cu₃Se₂ ↔ Cu_1.8Se ↔ 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.