A novel inorganic–organic polymer electrolyte with a high conductivity: insertion of poly(ethylene) oxide into LiV3O8 in one step

Abstract

A novel nanocomposite, PEO–LiV₃O₈, was synthesized by the intercalation of poly(ethylene) oxide (PEO) into the interlayers of LiV₃O₈ in one step. It was found that the two different components were combined on the nano-scale; the insertion of polymer was topotactic and did not cause structural changes in the layered host. The single-step weight loss (11.8 wt%) with TG/DSC measurement and other characterization results from XRD, FTIR, Raman, SEM, and TEM revealed that the putative molecular structure of PEO within the layers was similar to the zig-zag Type-I conformation of PEO–HgCl₂. The inserted PEO chains decreased the interaction of the negative V₃O₈⁻ layers with Li⁺ ions. Because a few interlayered PEO chains extended from the lamellae and connected further with each other, the adjacent PEO–LiV₃O₈ crystals were aggregated, thus providing a novel and suitable two-dimensional channel for Li⁺ ions to quickly transfer between the nancomposite grains. This particular hybrid structure of PEO–LiV₃O₈ resulted in an improvement of the electrochemical properties. The room temperature conductivity of PEO–LiV₃O₈ (2.99 × 10⁻⁴ S cm⁻¹) was superior to that of the conventional SPEs (LiClO₄–PEO, 1.1 × 10⁻⁷ S cm⁻¹) and the host material LiV₃O₈ (8.68 × 10⁻⁵ S cm⁻¹). Similar observations were also noted in other experimental parameters, such as the activation energy, diffusion coefficient of Li⁺ ions, and conductivity calculated by fitting EIS data.