Investigation of stability in high salt polymer electrolytes for sodium batteries

Sammanfattning: Poly(trimethylene carbonate)–sodium bis(fluorosulfonyl)imide system shows a promising performance as polymer-in-salt electrolytes. The polymer electrolytes with salts concentration from 62% to 71% were tested through DSC, FTIR, EIS and constant current cycling. The solubility of the salts varies in different salts in PTMC. The variation of thermal properties of samples is significant even from the same polymer piece. The measurements show saturation at coordination between Na+ and carbonate groups and ion conductivity at high salt concentrations. Cells with hard carbon and sodium metal electrodes are more stable than cells with Prussian white and sodium metal electrodes during cycling. Cells with 71% salt concentration polymer electrolytes have a good specific capacity and the best stability at 60°C.