Contribution of randomly oriented Li₂WO₄ with tetragonal symmetry to Li⁺ ion transfer resistance reduction in lithium-ion batteries

In this study, we used pulsed laser deposition to fabricate a thin-film electrode of LiCoO₂ (LCO) modified with lithium tungsten oxide (LWO). Then, to investigate the mechanisms underlying the low interfacial resistance of the modified electrode, we determined the diffusion coefficients of the Li⁺ ions in the bare and LWO-modified LCO and the three-dimensional structure of the LWO. Using electrochemical impedance spectroscopy, we determined that the LWO modification of the LCO enhanced the diffusion coefficient of the Li⁺ ions. XRD analysis showed that the LWO adopted a randomly oriented Li₂WO₄ structure with tetragonal symmetry displaying multiple Li⁺ ion diffusion paths, which contributed to enhancing the diffusion of Li⁺ ions between the positive electrode surface and liquid electrolyte, resulting in reduction of resistance to interfacial Li⁺ ion transfer.