Ab initio calculations for crystalline PEO6:LiPF6 polymer electrolytes

[Display omitted] •The atomic and electronic structures of crystalline PEO6:LiPF6 are obtained.•The diffusion pathway of lithium ions is determined with ab initio theory.•Li ions can pass within the cylinder channel with a low energy barrier.•The determined activation energy is 0.87 eV.•Calculations with ab initio DFT are consistent with the experimental data. Dry polymer electrolytes have been studied extensively because of their enhanced mechanical properties. Experimental studies have demonstrated that crystalline PEO6:LiPF6 has higher ionic conductivity than that of the amorphous phase, which seemingly contradicts the prevailing theory that amorphous polymer electrolytes have higher conduction performance. Also, the underlying mechanism at the atomic scale has remained elusive. In this work, the atomic and electronic structures of crystalline PEO6:LiPF6 are studied using ab initio density-functional theory. The results agree with experimental measurements. Additionally, the atomic-scale mechanisms of lithium ion transport in the polymer electrolytes are investigated with the climbing nudged elastic band method. The diffusion pathway and activation energy (∼0.87 eV) of lithium ions in crystalline PEO6:LiPF6 are determined.