New Insights on the Reversible Lithiation Mechanism of TiO2(B) by Operando X-ray Absorption Spectroscopy and X-ray Diffraction Assisted by First-Principles Calculations

Marcus Fehse (1) , Mouna Ben Yahia (1) , Laure Monconduit (1, 2) , Frédéric Lemoigno (1, 2) , Marie-Liesse Doublet (1, 2) , Florent Fischer (3) , Cécile Tessier (3) , Lorenzo Stievano (1, 2)

1 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 RS2E - Réseau sur le stockage électrochimique de l'énergie
3 SAFT [Bordeaux]

Operando X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) measurements provide new insights on the mechanism of lithium insertion into TiO2(B). The investigation of the evolution of electronic, long-range, and local structure during electrochemical cycling indicates a purely monophasic insertion mechanism upon lithium insertion, while global and local structure are only slightly modified. While XRD reflects an anisotropic lattice expansion, EXAFS reveals a wide distribution of Ti–O bond length, in line with the presence of two distinct distorted octahedral Ti environments, in agreement with previous DFT calculations. Upon lithium insertion, these Ti–O coordination shells undergo significant modifications which are enhanced once the insertion of 0.4 Li is exceeded, connoting a two regime process that is in good agreement with the electrochemical signature of this material. DFT calculations and local chemical bond analyses were coupled with experimental results, thus providing additional insights into the structural response of TiO2(B) upon lithiation.

Domaines: Matériaux

Marcus Fehse, Mouna Ben Yahia, Laure Monconduit, Frédéric Lemoigno, Marie-Liesse Doublet, et al.. New Insights on the Reversible Lithiation Mechanism of TiO2(B) by Operando X-ray Absorption Spectroscopy and X-ray Diffraction Assisted by First-Principles Calculations. Journal of Physical Chemistry C, 2014, 118 (47), pp.27210-27218. ⟨10.1021/jp507574e⟩. ⟨hal-01087975⟩