Battery Thermalization for Operando Synchrotron Powder Diffraction: Application to the Ca-TiS2 System

Abstract

Characterizing electrode materials and understanding its behavior during redox process is a key factor for battery improvement. In Situ techniques on Operando batteries are of particular interest since they do not only probe the material during the electrochemical process but avoid its hazardous and tedious extraction and transfer under inert atmosphere from an electrochemical cell to e.g. capillaries, to perform Ex Situ data collection. Synchrotron based techniques –absorption and diffraction – together with improved detectors, are now intensively used in such In Situ studies on Operando batteries since they allow fast and real time data acquisition during the electrochemical, ion (des-)insertion, process. So far most In Situ X-ray powder diffraction studies on Operando batteries are performed at room temperature using either coin cells or so called Leriche cells [1] (pouch cells, despite widely used for spectroscopy, are generally not favored for diffraction since the container material produce additional Bragg peaks). At ALBA we slightly modified both types of cells: Leriche type and more widespread used CR2032-type coin cells so as to perform data collection in temperature range -10° – 100° C. (see picture)Both types of cell have been used to study the intercalation of calcium in TiS2, previously determined by Ex Situ powder diffraction [2]. We managed to collect powder patterns operando at 60°C, 45°C and room temperature. (Des-)Insertion of solvated Ca2+ in TiS2 was favoured by temperature, its signature being the appearance of a new phase with a first diffraction peak at very low angles (~17.7 Å in terms of d-spacing). The process was found to be solvent dependent and reversible upon oxidation, which differs from Li cells where a similar process was observed.[3]Either of these thermalized cells can be used at CELLS-ALBA synchrotron for Power Diffraction on BL04-MSPD beamline or hard X-ray Absorption Spectroscopy (XANES/EXAFS) on BL22-CLEASS, and since 2023 also using simultaneous Powder Diffraction and hard X-ray Absorption Spectroscopy in BL16-NOTOS beamline. Moreover, the Leriche setup is also designed to fit for a use in laboratory X-ray diffractometers, in both reflection and transmission. Leriche et al. (2010). J. Electrochem. Soc., 157(5), A606-A610.Tchitchekova et al (2018). Chem. Mater 30, 847−856Houdeville et al. (2021). J. Electrochem. Soc., 168, 030514 Figure 1