The OPLS-AA (Optimized Potentials for Liquid Simulations All Atom) force field was used for all of the simulations. The parameters for LiTFSI were obtained from Leon et. al (nitrogen-coordinating TFSI point charges), while all of the polymers were parametrized through the LigParGen server for OPLS-AA parameters. An important aspect of MD simulations is the partial charge fitting scheme. The LigParGen server offers 1.14*CM1A semi-empirical charges, which were referred to as as LPG. We benchmarked the LPG charges against the commonly used Restrained Electrostatic Potential (RESP) charge fitting scheme (Figure ), referenced as DFT. To obtain the partial charges with the RESP fitting scheme, we generated an ensemble of 50 conformations for a 3-6 repeat unit n-mer with a short vacuum MD trajectory using the OPLS-AA interatomic potential parametrized with LigParGen under the NVT ensemble. We performed single point calculations with the ORCA quantum chemistry package on these conformations with the ωB97X-D rangeseparated hybrid functional with the def2-TZVP basis set and D3 dispersion correction. To obtain the RESP charges from the single point calculations we used the Multiwfn electronic wavefunction analysis software. As described earlier, having a long enough polymer chain length to be described by the reptation model is important for modeling chain-length-independent Li dynamics. For PEO, this length is at 110 monomer repeat units in the polymer backbone, which is almost 800 atoms in the polymer chain (molecular weight of around 5 kg/mol). Similar relationship has been established for some carbonate based polymer electrolytes, where the glass transition temperature tapers off for polymers with molecular weight larger than 1 kg/mol, and ion transport properties remain mostly independent of molecular weight larger than 4 kg/mol. To our knowledge the entanglement molecular weight has not been established for most other polymers evaluated in this paper, however, we applied the same approximation to the other mostly-linear polymer systems. As such, we modeled all of our polymer chains as having at least 1000 atoms in the chain (more than 6 kg/mol molecular weight).