Order-Disorder Transition in Rutile VO 2 (M) Electrodes during Li Intercalation and Extraction.

Transition metal oxides are widely employed as electrode materials in Li-ion batteries. During battery operation, Li ions are intercalated and extracted from the framework of the electrode structure, causing structural transitions. In some materials, the process can drive order-disorder transitions; however, insights into such processes are generally lacking, although they are essential for our understanding of battery aging and in the design of new sustainable battery chemistries. Herein, we investigate the intercalation-induced order-disorder transition in rutile VO 2 (M) electrodes by means of galvanostatic charge/discharge cycling, operando powder X-ray diffraction, and total X-ray scattering with pair distribution function analysis. The study reveals that the rutile structure transforms irreversibly into a highly disordered layered Li x VO 2 structure, which is capable of reversibly intercalating Li ions. Our findings point out general trends for the intercalation-driven transitions in rutile oxides.