Abstract
Single-ion conducting polymer electrolytes (SICPEs) are promising candidates for next-generation batteries due to their high lithium-ion transference number, which approaches unity. While their relatively low lithium-ion conductivity can be significantly enhanced by incorporating sufficient amounts of plasticizers, their thermal conductivity – crucial for effective thermal management in batteries – has received comparatively little attention. Adequate thermal conductivity is essential for rapid heat dissipation, helping to prevent heat accumulation that could potentially lead to thermal runaway. To investigate the conductivity behaviour of SICPEs, we performed both equilibrium and non-equilibrium Molecular Dynamics simulations to examine lithium-ion conductivity and thermal conductivity of modified polyethylene terephthalate–based SICPE in the presence of ethylene carbonate plasticizers. The simulated lithium-ion conductivities of SICPEs at different ethylene carbonate concentrations and temperatures show good agreement with experimental data, as does the thermal conductivity of the polyethylene terephthalate. Our results indicate that the addition of 50 wt% ethylene carbonate at 300 K provides an optimal balance, yielding a maximum thermal conductivity of 0.25 W/m/K–a small improvement over the unplasticized system—alongside a satisfactory lithium-ion conductivity of 2.94 × 10−4 S/cm. The enhanced lithium-ion conductivity is attributed to the weakened interactions between lithium ions and both ethylene carbonate molecules and polymeric backbone. Furthermore, the predominantly thermal conductivity medium shifts from polymer to ethylene carbonate upon loading ethylene carbonate. These insights advance the understanding of heat transfer behaviours in SICPEs and highlight the importance of thermal safety in their design and application.