Operando Investigation of the Lithiation Mechanism in CsPbCl3 Perovskite

Abstract

Metal halide perovskites offer a structurally responsive platform for lithium-ion battery components, however the interplay between structural transformation and electrochemical functionality remains poorly understood. Here, we investigate the lithiation mechanism in all-inorganic CsPbCl3 perovskite as a model system for resolving electrochemically driven phase reconstruction relevant to artificial solid electrolyte interphase concepts. Operando X-ray diffraction combined with electrochemical impedance spectroscopy, reveals that lithiation proceeds via a multistep pathway initiated by irreversible perovskite decomposition, resulting in formation of metallic Pb and mixed Cs–Li–Cl phases. Subsequently, reversible alloying reactions during the first cycle leads to the emergence of Li–Pb intermetallic compounds including LiPb and Li8Pb3. The evolution of diffraction features correlates with pronounced changes in the impedance response, revealing a transition from kinetically hindered conversion to more facile charge-transfer and diffusion-associated processes during alloying. Notably, no reconstruction of the perovskite framework is observed upon delithiation, confirming a conversion–alloying mechanism as the dominant charge-storage pathway. The in situ formation of Cs–Li–Cl phases coincides with marked changes in charge-transfer and diffusion-associated resistances, suggesting that the electrochemically generated chloride-rich products may contribute to the interfacial response of the reconstructed electrode. These results elucidate the lithium storage mechanism in halide perovskite-derived materials and highlight the role of decomposition-driven phase evolution in governing electrochemical performance.