Mechanistic Insight into the Self-healing Capability of Solid-State Lithium Batteries: Role of the PEO-TiO2 Interface

Abstract

Lithium dendrite formation during cycling of solid-state lithium batteries (SSLB) is known for critically affecting the duration of these devices, which limits their application, despite their promising overall performances. In this study, we performed a first-principles computational analysis of lithium interaction with anatase TiO2 surfaces grafted with polyethylendioxide (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 go also beyond a bare mechanical effect, as previously proposed, and also involve a chemical process of Li coordination and oxidation at the polymer/oxide interface.