Low-Temperature Brazing Strategy for High Voltage Na₄MnCr(PO₄)₃ Cathode-Based Solid-State Sodium-Ion Batteries

All-solid-state sodium-ion batteries (ASSIBs) with inorganic solid electrolytes can achieve high safety and high energy density when paired with a high-voltage cathode. However, the slow charge transfer and chemical instability between the high-voltage cathode and rigid electrolyte seriously restrict its development. Herein, a high energy density Na₄MnCr(PO₄)₃-based ASSIBs have been achieved by using a simple low-temperature brazing strategy. The in situ generated secondary phase can not only achieve close contact and rapid charge transfer between the Na₄MnCr(PO₄)₃ cathode and electrolyte but also change the interface electric field distribution and reduce interface side reactions effectively. This strategy is simple and easy to implement and has important guidance for the development of other high-energy all-solid-state batteries.