Electrochemical interfaces are highly complex, but important to understand to enable new and better battery technologies. Here, the structure and transport properties of the interface between Li metal and PEO-LiTFSI polymer electrolyte, including the electric double layer, are investigated by density functional theory computations and molecular dynamics simulations. Significant charge transfer is observed for a neutral short PEO chain when approaching the Li surface. The interfaces next to the negative and positive electrodes are different; the negative interface is being dominated by the polymer and Li+, while the anions make up more of the positive interface. Adsorption of Li+ ions on the Li slab is observed at high salt concentrations (0.98–3.56 mol L−1) and potential differences (0–4 V). The adsorption energy of the Li+ ions at the interface does not correlate with the Li+ transport kinetics, which is very slow, particularly next to the negative electrode. Slow interface kinetics might contribute to slow charge transfer and non-uniform Li plating. The adsorption of Li+ is only slightly affected by the electric potential difference between the electrodes.
Gullbrekken et al. (Fri,) studied this question.