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

摘要

Sodium metal batteries are promising for cost-effective energy storage,however, the sluggish ion transport in electrolytes and detrimental sodiumdendritegrowth stall their practical applications. Herein, a cross-linkingquasi-solid electrolyte with a high ionic conductivity of 1.4 mS cm~(?1) at 25 ℃is developed by in-situ polymerizing poly (ethylene glycol) diacrylate-basedmonomer. Benefiting from the refined solvation structure of Na+ with amuch lower desolvation barrier, random Na+ diffusion on the Na surface isrestrained, so that the Na dendrite formation is suppressed. Consequently,symmetrical Na||Na cells employing the electrolyte can be cycled >2000 hat 0.1 mA cm~(?2). Na_3V_2(PO_4)_3||Na batteries reveal a high discharge specificcapacity of 66.1 mAh g~(?1) at 15 C and demonstrate stable cycling over1000 cycles with a capacity retention of 83% at a fast rate of 5 C.