UV-Cross-Linked Ionogels for all-solid-state rechargeable sodium batteries

© 2019 American Chemical Society. 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-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide and sodium bis(fluorosulfonyl)imide is demonstrated. The ionogels showed very high ionic conductivity at 50 °C (6.5 × 10-3 S·cm-1) close to the liquid counterpart (7.8 × 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 °C with good capacity retention.