Deciphering the Interface Failure Mechanism for Aqueous Na-Ion Batteries at Low Temperatures

Recently, advances in simply lowering the freezing point of dilute aqueous electrolytes have somewhat improved the low-temperature performance of aqueous Na-ion batteries (ANIBs), which promote applications in grid-scale energy storage across multiple scenarios. However, the inconsistency between the freezing points of the electrolytes and the stable operating temperature range for most batteries suggests that there are other crucial factors at play. In this work, we redirect our efforts toward elucidating the intricate interfacial aspects by employing diverse electrode types and electrolytes with varying concentrations. Along this line, a "selective interface blocking" mechanism is proposed for battery failure at low temperatures, involving the independent precipitation of ice on the anode side and salt on the cathode side at high potentials, regardless of frozen electrolytes. Our research sheds new light on the intricate relationship between interfaces and low-temperature performance, redefining and systematically constructing the failure mechanism in ANIBs.