Electrochemical Performance of Orthorhombic CsPbI Perovskite in Li-Ion Batteries.

A facile solution process was employed to prepare CsPbI as an anode material for Li-ion batteries. Rietveld refinement of the X-ray data confirms the orthorhombic phase of CsPbI at room temperature. As obtained from bond valence calculations, strained bonds between Pb and I are identified within PbI octahedral units. Morphological study shows that the as-prepared δ-CsPbI forms a nanorod-like structure. The XPS analysis confirm the presence of Cs (3d, 4d), Pb (4d, 4f, 5d) and I (3p, 3d, 4d). The lithiation process involves both intercalation and conversion reactions, as confirmed by cyclic voltammetry (CV) and first-principles calculations. Impedance spectroscopy coupled with the distribution function of relaxation times identifies charge transfer processes due to Li metal foil and anode/electrolyte interfaces. An initial discharge capacity of 151 mAhg is found to continuously increase to reach a maximum of ~275 mAhg at 65 cycles, while it drops to ~240 mAhg at 75 cycles and then slowly decreases to 235 mAhg at 100 cycles. Considering the performance and structural integrity during electrochemical performance, δ-CsPbI is a promising material for future Li-ion battery (LIB) application.