Pyrolysis characteristics and kinetics of polymethylmethacrylate-based polymer electrolytes for lithium-ion battery

Polymethylmethacrylate (PMMA) is a common polymer electrolyte matrix material whose pyrolysis characteristics are vital factors affecting the development of PMMA-based polymer electrolytes. In this study, four polymer electrolytes based on PMMA were prepared. Electrochemical workstation was used to verify the electrochemical performance of PMMA-based polymer electrolytes Fourier-transform infrared spectroscopy was adopted to assess the changes of pure polymer and polymer electrolyte groups, and the synchronous thermal analyzer was used to analyze the pyrolysis characteristics of PMMA-based polymer electrolytes. The apparent activation energy of PMMA-based polymer electrolyte was calculated by Kissinger method and FWO method, and the integral method Coats–Redfern was used to determine the pyrolysis mechanism function of the main pyrolysis stage. The results revealed that PMMA-based polymer electrolytes had two or three pyrolysis stages at high temperature. The PMMA composite gel polymer electrolyte had the highest thermal stability, whereas the gel polymer electrolyte had the lowest apparent activation energy. The apparent activation energy was 235.9 and 127.8 kJ mol⁻¹ for PMMA composite electrolyte and PMMA gel polymer electrolyte, respectively. The main pyrolysis mechanism of PMMA-based polymer electrolytes was third-order reaction and three-dimensional diffusion reaction.