Mg ion conducting solid polymer electrolyte for advanced energy storage system*

Magnesium (Mg) batteries have the potential to replace the Li-ion technology because of superior safety and high abundance of Mg metal. However, the commercialization is hindered due to lack in development of electrolyte and cathode systems. A novel highly conductive, solvent-free, solid state polymer Mg ion electrolyte for advanced energy storage application is developed. Mg-ion conducting solid state polymer electrolytes (SPE) comprised of polyethylene glycol diacrylate (PEGDA) prepolymer, magnesium bis(trifluoromethanesulfonyl) imide (Mg(TFSI)₂) salt, and succinonitrile (SCN) plasticizer were systematically examined. Optimization of composition for solid polymer electrolyte to achieve superionic conductivity was performed in the isotropic region guided by ternary phase diagram. Addition of plasticizer decreases T_gof the system, but it increases the ionic conductivity. By using various plasticizers and mixed Mg/Li salts in the development of SPE, the effect of plasticization and salt composition on the ionic conductivity, electrochemical stability window, thermal stability and mechanical properties will be demonstrated.