Vanadium K-Edge X-ray Absorption Spectroscopy as a Probe of the Heterogeneous Lithiation of V2O5: First-Principles Modeling and Principal Component Analysis

Understanding the diffusion mechanisms of Li ions through host materials and the resulting phase evolution of intercalated phases is of paramount importance for designing electrode materials of rechargeable batteries. The formation of lithiation gradients and discrete domains during intercalation leads to the development of strain within the host material and is responsible for the observed capacities of most cathode materials being well below theoretically predicted values. Such mesoscale heterogeneity has also been implicated in the loss of capacity upon cycling. Due to their inherent complexity, the analysis of such heterogeneity is rather complex and precise understanding of the evolution of metal sites remains underexplored. In this work, we use phase-pure, single-crystalline V2O5 nanowires with dimensions of 183 ± 50 nm and lengths spanning tens of microns as a model cathode material and demonstrate that V K-edge X-ray absorption near-edge structure can be used as an effective probe of the local val...