Effect of Disorder and Doping on Electronic Structure and Diffusion Properties of Li3V2O5

V2O5 in its omega phase (Li3V2O5) with excess lithium is a potential alternative to the graphite anode for lithium-ion batteries at low temperature and fast charging conditions owing to its safer voltage (0.6 V vs Li+/Li(s)) and high lithium transport rate. In-operando cationic disorder, as observed in most ordered materials, can produce significant changes in charge compensation mechanisms, anionic activity, lithium diffusion, and operational voltages. In this work, we report the variation in structural distortion, electronic structure, and migration barrier accompanied by disorder using first-principles calculations. Owing to the segregation of lithium atoms in the disordered state, we observe greater distortion, emergence of metallic behavior, and potential anionic activity from nonbonding oxygen states near the Fermi level. Redox capacity can be tuned by doping with 3d metals, which can adjust the participating cationic states, and by fluorine substitution, which can stabilize or suppress anionic states. Moreover, the suppression of anionic activity is found to decrease structural distortion, which is crucial for mitigating voltage fade and hysteresis. Diffusion barrier calculations in the presence of disorder indicate the activation of the remaining 3D paths for lithium hopping which are unavailable in the ordered configuration, explaining its fast-charging ability observed in experiments.

Automated summary

In this study, the variation in structural distortion, electronic structure, and migration barrier accompanied by disorder in V2O5 was investigated using first-principles calculations. The segregation of lithium atoms in the disordered state led to greater distortion, emergence of metallic behavior, and potential anionic activity. Redox capacity can be tuned by doping with 3d metals and fluorine substitution, which can adjust participating cationic and anionic states, respectively. The suppression of anionic activity was found to decrease structural distortion, which is crucial in mitigating voltage fade and hysteresis. Diffusion barrier calculations in the presence of disorder explained the fast-charging ability observed in experiments.