Tailored Heterogeneous Interphase Layer Promotes Low-Temperature Desolvation Toward Durable Sodium Metal Batteries

Sodium metal batteries (SMBs) represent a promising next-generation energy storage technology due to their low cost and high energy density. However, SMBs face significant challenges, including interfacial instability and the growth of sodium dendrites on the metal anode, particularly at low temperatures (LTs). Poor ion desolvation at LTs further exacerbates these issues, severely compromising battery performance. To address these problems, a heterogeneous artificial solid electrolyte interphase (SEI) composed of Na₃VO₄ and metallic In (NVO-In@Na) is designed for LT SMBs. The sodiophilic Na₃VO₄ promotes sodium ion adsorption, while the Na₂In phase formed during the initial plating enhances ion transport kinetics, resulting in uniform Na deposition behavior. Theory calculations indicate that the Na₃VO₄/Na₂In interface accelerates charge transfer processes and desolvation. The engineered NVO-In@Na anode demonstrates exceptional stability: symmetric cells operate for over 2000 h at 0.5 mA cm^-2/1 mAh cm^-2 under ambient conditions and exceed 1100 h at 0.1 mA cm^-2/0.1 mAh cm^-2 at -40 °C. Full cells paired with Na₃V₂(PO₄)₃ (NVP) cathode retain 97% capacity after 1150 cycles at 0.5 C and -40 °C. This work highlights the potential of rational SEI design to overcome critical limitations of SMBs, advancing high-performance energy storage under extreme conditions.