“Preferential adsorption-decomposition and strong binding” strategy-derived interphase enabling fast-charging and wide-temperature sodium metal batteries

The interface reaction that occurs between electrodes and electrolyte is a significant factor to the degradation of batteries' electrochemical performance. One crucial avenue to enhance the electrochemical performance of sodium metal batteries (SMBs) is to construct robust inorganic-rich interphases that can effectively inhibit interface side reactions. Herein, we report and demonstrate a collaborative strategy called “Preferential Adsorption-Decomposition and Strong Binding” (ADSB) that is based on sodium fluorophosphate (Na₂PO₃F, safe and non-toxic, can be utilized as an anti-caries agent in toothpaste.), a multifunctional anionic additive that preferentially adsorbs on the inner Helmholtz plane (IHP), preferentially decomposes, and contributes to the solvation structure to form a multi-anion solvated sheath. Based on the ADSB strategy, the robust electrode electrolyte interphases are successfully constructed on the surface of Na₄Fe₃(PO₄)₂P₂O₇ (NFPP) and sodium-metal. Consequently, at an extremely high rate of 50 C, the NFPP||Na cell with Na₂PO₃F modified electrolyte achieves a high capacity of 60.9 mAh g^-1. Furthermore, the stable interphases derived from Na₂PO₃F are resistant to wide-temperature. At -40 °C, the NFPP||Na cell demonstrates a high capacity of 73.0 mAh g^-1, and after 200 cycles at 60 °C, it achieves 84.2% capacity retention.