Developing a high-voltage electrolyte based on conjuncto-hydroborates for solid-state sodium batteries

Na 2 B 20 H 18 was explored as a solid electrolyte and showed remarkable electrochemical stability up to 5.1 V vs. Na + /Na. Na 2 B 20 H 18 /Na 2 B 12 H 12 achieved an ionic conductivity of 2.8 × 10 −4 S cm −1 and an electrochemical window beyond 4.8 V.