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

Abstract

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 ( R 2 ) 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 ( λ Li+ ) 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 λ Li+ , the better the ionic conductivity. The maximum λ Li+ 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.