Investigating the Phase Transition of VO2(M) to VO2(R) Via Lithium-Ion Electrochemistry

Abstract

Vanadium dioxides exist as different polymorphs, each with unique electrochemical properties. Herein, we investigate the monoclinic to rutile transition of vanadium dioxide using different temperatures. The transition from monoclinic to rutile is characterized using synchrotron-based X-ray diffraction and electrochemical performance is performed using electrochemical impedance spectroscopy and intermittent pulsatile galvanostatic discharge tests in a lithium-ion environment. The experimental results indicate a decrease in ohmic resistance when lithium-ion cells are tested at higher temperatures. Density functional theory calculations also identified a possible LixVO2(M) to LixVO2(R) phase transition during the discharging process. Since the monoclinic to rutile transition corresponds to an increase of electrical conductivity by 2 orders of magnitude this can favorably impact the function of a lithium-based electrochemical cell.