Investigation of a UV-cured PEGDA-based solid polymer electrolyte for high-voltage solid-state battery applications

Abstract

Solid polymer electrolytes (SPE) are considered a promising material for next-generation solid-state batteries due to their safety and compatibility with the lithium anode. However, their low electrochemical stability window and poor interfacial compatibility prevent their application for high-voltage battery systems. This study investigates the potential of a UV-cured poly(ethylene glycol) diacrylate (PEGDA) based polymer electrolyte for high-voltage solid-state batteries. The electrolyte was evaluated using electrochemical characterization techniques, including linear sweep voltammetry (LSV) to determine its electrochemical stability window and electrochemical impedance spectroscopy (EIS) to assess ionic conductivity. The results revealed that the PEGDA-based electrolyte exhibits good ionic conductivity at elevated temperatures. In contrast, no clear oxidation onset could be determined from the LSV measurement over a potential range of 0-5 V. A possible explanation is related to the electrolyte composition, as the electrolyte exhibited poor mechanical integrity and handling characteristics, which may have resulted in poor electrode-electrolyte contact. To investigate the hypothesis, a second PEGDA-based electrolyte was synthesized by replacing the plasticiser and adjusting the compositional ratio. The modified version gives a clear curve at 4.6 V in the stainless steel/solid polymer electrolyte/lithium (SS/SPE/Li) configuration at the scan rate of 0.1 mV/s. In addition, the new electrolyte demonstrated qualitatively improved handling characteristics compared with the initial formulation. These findings suggest that the composition plays a critical role in ionic conductivity, electrochemical stability, and mechanical properties of the electrolyte system. However, further studies are required to optimize the formula and to verify the suitability for high-voltage lithium batteries.