Quantum mechanical insight into the Li‐ion conduction mechanism for solid polymer electrolytes

Abstract Ion transport in polymeric electrolytes (PEs) has been studied for approximately a half century, yet the ion conduction mechanism in the PEs is not fully understood. Herein, we report a new approach to understand the ion migration process in poly (ethylene oxide)/Lithium bis(trifluoromethane sulphonyl) imide (PEO/LiTFSI) and poly (ethylene oxide)/Lithium bis(oxalate) borate (PEO/LiBOB) electrolytes based on quantum mechanics. The results show that the coefficient of determination (R2) obtained from the new model exceeds 0.99 for all the PEs, which is far higher than these obtained from the well‐known Arrhenius and Vogel‐Tammann‐Fulcher (VTF) equations. The wavelength (λLi+) of Li‐ion migrations or the distance between the occupied site and the neighboring partially‐occupied site is the most crucial factor to affect the ionic conductivity of PEs. The higher the λLi+, the better the ionic conductivity. The maximum λLi+ value of the PEs approximates angstrom order of magnitude. The developed ion conduction model opens an avenue to design PEs with a higher ionic conductivity.