Regulating Na‐ion Solvation in Quasi‐Solid Electrolyte to Stabilize Na Metal Anode

Abstract Sodium metal batteries are promising for cost‐effective energy storage, however, the sluggish ion transport in electrolytes and detrimental sodium‐dendrite growth stall their practical applications. Herein, a cross‐linking quasi‐solid electrolyte with a high ionic conductivity of 1.4 mS cm −1 at 25 °C is developed by in‐situ polymerizing poly (ethylene glycol) diacrylate‐based monomer. Benefiting from the refined solvation structure of Na + with a much lower desolvation barrier, random Na + diffusion on the Na surface is restrained, so that the Na dendrite formation is suppressed. Consequently, symmetrical Na||Na cells employing the electrolyte can be cycled >2000 h at 0.1 mA cm −2 . Na 3 V 2 (PO 4 ) 3 ||Na batteries reveal a high discharge specific capacity of 66.1 mAh g −1 at 15 C and demonstrate stable cycling over 1000 cycles with a capacity retention of 83% at a fast rate of 5 C.