Thermally Stable Artificial Solid Electrolyte Interphase With Tailored Sodiophilicity and Solvent‐Philicity for Stable Sodium Metal Batteries

ABSTRACT Artificial interphases are promising for dendrite suppression in sodium (Na) metal batteries. However, they are impeded by challenges such as poor thermal stability, inadequate sodiophilicity and solvent‐philicity, and uncontrollable active Na loss via alloying/conversion reactions. Herein, we designed a P 3 N 5 ‐based interphase to achieve dendrite‐free and thermally safe Na metal batteries. This P 3 N 5 interphase exhibits high Young's modulus and thermal stability, allowing it to withstand thermal abuse and mechanical stress. Its strong sodiophilicity and solvent‐philicity can reduce nucleation barrier, accelerate Na + desolvation, and homogenize Na + flux. Moreover, the fabrication of the P 3 N 5 layer avoids conventional alloying/conversion reactions, ensuring high Na utilization efficiency and excellent interfacial stability. Consequently, the P 3 N 5 @Na (PN@Na) anode achieves stable cycling for 720 h at 25°C and 580 h at 45°C (1.0 mA cm −2 ). Even at 100°C, it can remain stable for over 45 h (1.0 mA cm −2 ). The Na 3 V 2 (PO 4 ) 3 (NVP)||PN@Na cell at 25°C enables a rate capacity of 63.7 mAh g −1 (50 C) and maintains 93.1% capacity after 2000 cycles (20 C). At 45°C, the cell can also operate stably for 400 cycles. This work provides practical guidance for developing robust interfaces toward dendrite‐free and thermally safe Na metal batteries.