December - 20198 MANUFACTURING TECHNOLOGY INSIGHTSIN MY OPINIONIn situ and operando X-ray Diffraction gives insight into mechanisms for battery performanceBy Stefan Seidlmayer, TU München, Heinz Maier-Leibnitz Zentrum (MLZ) Garching, and Fabio Masiello, Malvern PanalyticalThe long-term performance of lithium-ion batteries is crucial for applications in new markets such as energy storage in electric vehicles and large-scale electronic storage devices. A vital requirement of these applications is excellent long-term and cycling performance. For studying complex aging processes in batteries, the process heavily depends on minuscule changes in cell chemistry and material composition and ideally requires monitoring the structural evolutions of both anode and cathode electrodes at the same time. In situ and operando XRD X-ray diffraction (XRD) is a powerful tool for the characterization of battery materials. XRD is a laboratory technique using monochromatic X-rays to probe atoms in a material to reveal structural information, such as crystal form, lattice dimensions, crystallite size, defects in the crystal structure, and preferred orientation of crystalline material. XRD instruments, like the Empyrean diffractometer as shown in Figure 1, can be used to conduct in-depth structural analysis and makes it possible to identify the different phases present in battery materials. In situ XRD analysis allows the structural analysis of electrode materials within the electrochemical cell at specific states of charge. The operando (Latin word for "operating") technique enables the characterization of the structural evolution of the crystalline phases contained in battery cells, simultaneous with the operation of the reaction. XRD transmission measurements using hard radiation (e.g., from a Mo or Ag anode X-ray tube) provide the ability to penetrate sufficiently through working batteries during charge and discharge cycling and follow the Li uptake of cathode and anode. Coin cells, prismatic batteries such as those found in a cell phone, or pouch cells are all suitable for XRD in situ / operando analysis.Figure 1. Malvern Panalytical's Empyrean diffractometerStefan Seidlmayer
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