Mechanisms of Lithium Intercalation and Conversion Processes in Organic-Inorganic Halide Perovskites

Organic-inorganic halide perovskites are attracting extraordinary attention in the field of energy materials. The reaction of hybrid lead halide perovskites with Li metal has recently been proposed for a number of potential applications. However, the mechanisms for Li uptake in such materials, such as intercalation and conversion, are still unknown. Using a combination of density functional theory and electrochemical and diffraction techniques, we consider Li intercalation and conversion reactions in CH₃NH₃PbI₃, CH₃NH₃PbBr₃, and CH₃NH₃PbCl₃. Our simulations suggest that conversion reactions with Li are far more energetically preferable in these materials than Li intercalation. Calculations confirm the formation of Pb metal as a result of Li conversion in all three materials, and this is supported by X-ray diffraction analysis of CH₃NH₃PbBr₃. The results of this study provide fresh insights into lithium and halide perovskite reactions that will hopefully drive further exploration of these materials for a wider variety of energy applications.