Operando investigations of lithiation and delithiation processes in a BiVO4 anode material

Abstract

BiVO₄ undergoes a series of conversion and alloying reactions as an anode material in lithium ion batteries. The current work demonstrates a charge capacity of 485 mA h g⁻¹ after 50 cycles in a voltage range of 0–2.00 V (graphite has a capacity of 372 mA h g⁻¹ theoretically). An exceptionally high volumetric capacity makes BiVO₄ suitable for compact applications (volumetric capacity of 3984 mA h cm⁻³ for BiVO₄ in comparison to 756 mA h cm⁻³ for graphite theoretically). Reaction steps and electronic transformations have been identified by operando quasi simultaneous synchrotron X-ray diffraction and absorption spectroscopy studies. An irreversible reaction step occurs for the Bi³⁺/Bi⁰ redox pair, whereas reversible mechanisms are found for the V⁵⁺/V³⁺ and Bi⁰/Bi³⁻ redox pairs. The proposed mechanisms are supported by density functional theory (DFT) calculations.