Mechanistic insight into the self-healing capability of solid-state lithium batteries: role of the PEO–TiO2 interface

Lithium dendrite formation during cycling of solid-state lithium batteries (SSLB) is known to critically affect the duration of these devices, which limits their application, despite their promising overall performance. In this study, we performed a first-principles computational analysis of lithium interaction with anatase TiO2 surfaces grafted with polyethylene oxide (PEO) – aiming at understanding the mechanism behind the self-healing behavior observed in batteries with composite electrolytes comprising nanoparticles of functionalized titania. We report a strong stabilization of Li species at the PEO/TiO2 interface, which exposes several oxygen sites with good coordinative capability toward Li+ cations, whose formation is enabled by the reducible nature of TiO2, prone to host extra electrons in the empty Ti(3d) states. The role of PEO/TiO2 nanostructures in dissolving dendrites, thus, may not be limited to a bare mechanical effect, as previously proposed, and also involves a chemical process of Li coordination and oxidation at the polymer/oxide interface.