UV-Cross-Linked lonogels for All-Solid-State Rechargeable Sodium Batteries

A simple method to prepare a mechanically robust ionogel film by fast (<1 min) UV photopolymerization of poly(ethylene glycol) diacrylate in the presence of an ionic liquid electrolyte based on N-propylN-methylpyrrolidinium bis(fluorosulfonyl)imide and sodium bis(fluorosulfonyl)imide is demonstrated. The ionogels showed very high ionic conductivity at 50 degrees C (6.5 x 10(-3) S.cm(-1)) close to the liquid counterpart (7.8 X 10(-3) S.cm(-1)). High salt concentration in the ionogels was beneficial for the sodium plating and stripping. Na/ionogel/NaFePO4 full cells delivered a high specific capacity of 152 mAh g(-1) at 50 degrees C with good capacity retention.