Study of the insertion mechanism of lithium into anatase by operando X-ray diffraction and absorption spectroscopy

•Analysis of Li + insertion mechanism of anatase via operando XRD and XAS•Three domains of lithium insertion into anatase were identified by XRD.•Electronic and local structure changes were monitored by XANES.•EXAFS reveals modification of local structure during biphasic transformation domain.•No tetragonal LiTiO2 is formed although > 0.7 Li + was inserted.

Operando X-ray diffraction (XRD) and X-ray absorption (XAS) were used to study Li+ insertion into TiO2 anatase during electrochemical cycling in a Li cell. The evolution of long range order and local structure with the amount of lithium reacted were analyzed to identify and characterize the individual insertion domains. These results agree with a three-step insertion process, firstly solid solution, followed by characteristic biphasic plateau corresponding to the transformation from tetragonal to orthorhombic phase which is succeeded by a monophasic insertion.