Operando Measurement of Laminated Lithium-ion Battery using 2DD

Application Note B-XRD1116

Introduction

To develop lithium ion secondary batteries with high capacity, high reliability, and long life, it is essential to evaluate the stability of the electrode materials during the charge/discharge process. The laminate cell attachment enables the reproduction of a high-speed charge/discharge process while keeping the sample temperature constant, and simultaneously allows the collection of transmission X-ray diffraction images. Using this attachment with an X-ray diffractometer equipped with a Mo X‑ray source and a 2D detector collecting up to 131 diffraction images per second, it is possible to observe the rapid phase transition occurring inside the battery cell.

Measurement and result

Figure 1 shows a photo of the laminate cell attachment and the 2D detector. LiFePO₄ was selected as the positive electrode. Measurement using an exposure time of 10 sec was repeated while charging/discharging the laminate cell at 2C/1C (Here, 1C denotes the current based on ampere-hour rating for total charge / discharge in 1 hour, e.g. the charge at 2C completes in 0.5 hours and discharge at 0.5C does in 2 hours. ) Figure 2 shows a 2D diffraction image observed during the charging process. Diffraction signals characteristic to FePO₄ and LiFePO₄ were observed in the region indicated by the dotted line. Figure 3 shows the profile map of the region marked in Figure 2, the voltage graph and the diffraction peak intensities of FePO₄ and LiFePO₄. It was confirmed that the electrode material returned to the same crystal phase as before the measurement started. 

B-XRD1116 Figure 1 Laminate cell attachment
Figure 1: Laminate cell attachment. 


B-XRD1116 Figure 2 A 2D diffraction image observed in the charging process.
Figure 2: A 2D diffraction image observed in the charging process. 


B-XRD1116 Figure 3 Profile map voltage graph and diffraction peak intensity
Figure 3: The profile map, voltage graph and diffraction peak intensity of FePO₄ and LiFePO₄. 

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