Sodiophilic Interface Induces a NaF-Rich Solid Electrolyte Interface for Stable Sodium–Metal Batteries under Harsh Conditions

Abstract

The development of sodium–metal batteries faces challenges, particularly Na dendrite growth resulting from uneven Na plating/stripping and side reactions between Na metal and the electrolyte. Herein, a Ag interfacial layer on the sodium metal surface is proposed. Benefiting from its excellent sodiophilicity, the Ag coating works as nucleation sites that guide uniform Na deposition. Simultaneously, the excellent conductivity of Ag ensures a homogeneous electric field distribution and Na ion flux, which also contribute to uniform Na deposition. Furthermore, the strong interaction between Ag and PF₆^– induces the construction of a NaF-rich solid electrolyte interphase, which contributes to stabilizing the interface and suppressing the side reactions. Consequently, the symmetric cells demonstrate high cycling stability over 1000 h at 3 mA cm^–2. Moreover, the full cells achieve an impressive capacity retention rate of 90% after 800 cycles at 20 C and demonstrate excellent performance even across various temperatures.