An All-Phosphate and Zero-Strain Sodium-Ion Battery Based on Na 3 V 2 (PO 4 ) 3 Cathode, NaTi 2 (PO 4 ) 3 Anode, and Trimethyl Phosphate Electrolyte with Intrinsic Safety and Long Lifespan.

Development of intrinsically safe and long lifespan sodium-ion batteries (SIBs) is urgently needed for large-scale energy storage applications. However, most of the currently developed SIBs suffer from insufficient cycle life and potential unsafety. Herein, we construct an all-phosphate sodium-ion battery (AP-SIB) using a Na ₃ V ₂ (PO ₄ ) ₃ cathode, NaTi ₂ (PO ₄ ) ₃ anode, and nonflammable trimethyl phosphate (TMP) electrolyte. The AP-SIB exhibits not only high safety, high rate performance, and ultralong cycle life but also zero-strain characteristics due to the inverse volume change of the phosphate cathode and anode during charge and discharge cycles, offering a safer and cycle-stable Na-ion technology for electric storage applications.