Simultaneous in Situ X-ray Absorption Spectroscopy and X-ray Diffraction Studies on Battery Materials: The Case of Fe_0.5TiOPO₄

Abstract

Following the reaction mechanisms of materials for Li-ion batteries under in situ conditions can provide vital new clues in the development of better battery materials. A new in situ cell was developed for such a purpose which allows an almost simultaneous measurement of XRD (X-ray diffraction) and XAS (X-ray absorption spectroscopy) at energies as low as the Ti K-edge. Change from one method to the other was possible in less than a minute at the Swiss–Norwegian Beamline (SNBL). Using this cell with its flexibility in terms of windows, it was proven that the reaction mechanism of iron titanium oxyphosphate (Fe0.5TiOPO4) upon lithiation and delithiation consists of a combined insertion–conversion reaction with the mostly reversible reduction of Ti4+ to Ti2+ and Fe2+ to Fe0.

Electrochemical characterizations of Co0.5TiOPO4 as anode material for lithium-ion batteries

“…According to the previous work on this family of materials like Ni 0.5 TiOPO 4 , Fe 0.5 TiOPO 4 and Cu 0.5 TiOPO 4 [18,23,28,29], the first large discharge capacity is related to the Ti 4 þ ions reduction to Ti 3 þ and Ti 2 þ , in parallel with the Co 2 þ reduction to Co°. In addition, the electrolyte decomposition occurring at low voltage and leading to the SEI layer (Solid Electrolyte Interface) formation is another source of the lithium uptake, as confirmed by our group for Ni 0.5 TiOPO 4 /C anode material [23].…”

Charge/discharge Behavior of Triclinic LiTiOPO₄ Anode Materials for Lithium Secondary Batteries

“…1 On the other hand, Ti-based MB 0.5 TiOPO 4 (MB = Fe, Co, Ni, or Cu) materials have been researched and developed as high-capacity anode materials for lithium secondary batteries. [2][3][4][5][6][7][8][9] Y. Kee and coworkers reported the synthesis of rhombohedral LiTi 2 (PO 4 ) 3 and orthorhombic Li 1.5 Ti 2 (PO 4 ) 3 via the sol-gel method and the investigation of their use as anode materials for rechargeable Liion batteries. 10 S. Patoux and C. Masquelir reported that LiTiPO 5 / Super P carbon (SP carbon; MMM Carbon, Belgium) electrodes worked as active materials using cyclic voltammetry (CV) measurements and galvanostatic intermittent titration techniques (GITT).…”

In situ X-ray diffraction characterisation of Fe0.5TiOPO4 and Cu0.5TiOPO4 as electrode material for sodium-ion batteries

“…The material turns amorphous quite rapidly with the reaction with the 1 st Na + per f.u. No intermediate phase of Fe0.5TiOPO4 is formed as demonstrated for Li-ion batteries [2]. The amorphisation is irreversible and during desodiation no further hint about the reaction mechanism can be found by in situ XRD.…”

“…Prior to in situ measurement, a careful analysis of structure of the synthetized powders (Fe0.5TiOPO4 and Cu0.5TiOPO4) can be found here [2,9]. A summary of those data is reported in the supplementary material.…”

“…upon the first lithiation and 3 Li + per f.u. in the first delithiation in a combined insertion-conversion type reaction [2,3]. However, the potential of the reaction of those materials is not suitable for a commercial application in Li-ion batteries.…”