Ionic Liquid-Supported Single-Sodium-Ion-Conducting Styrene-Maleic Anhydride Copolymer for Energy Storage Devices

Abstract

Wide-ranging research has been done on ionic liquid (IL)-incorporated conducting polymers in energy storage devices. Herein, by taking the reaction advantage of styrene maleic anhydride (SMA) copolymer with sodium hydroxide, a sodium ion having polymeric material as an electrolyte is synthesized. 1,8-Diazabicyclo[5.4.0]undec-7-enium acetate (DBU acetate) is prepared as an IL and added to the prepared polymer electrolyte to increase the matrix flexibility, semisolid nature, and ionic mobility inside the matrix. This semisolid sodium ion-based electrolyte shows conductivity in the order of 10⁻⁵S cm⁻¹ and an electrochemical stability window of 2.52 volts with >97% of ionic transference. It also shows the diffusivity constant in the order of 10⁻⁴ m² s⁻¹ and ionic mobility in the order of 10⁻³ m² v⁻¹s⁻¹ at 30 °C. The hydrogel matrix shows a correlated type of hopping with a power exponent <1 at 30 °C with low-energy requirement of ionic transport, that is, 0.709 eV. A high amount of capacitance is associated with electrolyte that has an insignificant electrode contribution. On behalf of these findings, SMA-IL-based semisolid polymer electrolyte confirms its potential for application in sodium ion-based energy storage systems.