Unveiling an Innovative Pathway for Enhancing Lithium-ion Conductivity of Li

Solid-state lithium-ion batteries have raised considerable attention due to their great potential for the development of new energy storage devices with high energy density and safety. However, enhancing ion conductivity in solid-state electrolytes stands as a pivotal challenge for the large-scale commercialization of next-generation lithium-ion batteries. Here, a high-pressure strategy is reported to achieve the significant enhancement of lithium-ion conductivity by 2 orders of magnitude and the disappearance of grain boundary resistance in polyoxometalate Li3PW12O40 electrolyte via an irreversible phase transition from Keggin to bronze structure. High-pressure in situ structure analyses revealed that the Keggin structure started to transform into the bronze structure at 18.0 GPa, and completed the transition around 34.0 GPa. Detailed density functional theory (DFT) calculations indicated that the bronze structure captured under pressure had a lower migration barrier (0.051 eV) and activation energy (0.091 eV) than the Keggin structure, which was mainly attributed to the corner-sharing WO6 octahedra and PO4 tetrahedra forming tunnels that can accommodate Li+ ions and provide transport channels. These results not only offer novel insights into optimizing the ion conductivity of solid-state electrolytes but also hold promise for developing new electrolyte materials under pressure.