Operando Measurement of Li Ion Battery Positive Electrode in Charge/Discharge Process by X-ray Diffraction

September 1, 2018



This application note demonstrates the measurement by X-ray diffraction (XRD) of positive electrode material from lithium ion batteries during the charge/discharge process.

Lithium ion secondary batteries are widely used in small portable devices such as mobile phones. Research and development of lithium ion batteries for use in automobiles and larger machines is an active field. To develop lithium ion secondary batteries with high capacity, high stability and long life, it is essential to evaluate the stability of the positive electrode material during the charge/discharge process. Operando X-ray diffraction measurements using an attachment that reproduces the charge/discharge environment and a 2D detector that can perform high-speed measurements enables detailed observation of crystal phase changes while a battery is in use, making it suitable for studying battery performance and life.


Figure 1: Figure 1 shows a picture and an illustration of the cross-sectional structure of a battery cell attachment. The positive electrode material was LiMn1.5Ni0.5O4. Measurement using an exposure time of 15 s was repeated while charging/discharging the electrode at a charge and discharge rate 1C = 132 mAh/g. Changes to the X-ray diffraction profile over time were investigated.

Experimental Conditions

X-ray diffraction measurements of the positive electrode material during high-speed charging and discharging were carried out with a battery cell attachment and a HyPix-3000 2D detector on a Rigaku SmartLab X-ray diffractometer.


Figure 2: Figure 2 shows the multiple 1D XRD profiles, 2D profile maps and voltage graphs. Two steps of a two-phase coexistence reaction occurred with charging and discharging. After charging and discharging, the electrode material returned to the same crystal phase as before the measurement started.

Conclusion

The Rigaku SmartLab Automated multipurpose X-ray diffractometer with HyPix-3000Hybrid pixel array multi-dimensional detector can perform high-speed Operando measurements of crystal phase changes of lithium ion batteries to evaluate battery performance and life.


Figure 3: Rigaku SmartLab automated multipurpose X-ray diffractometer (XRD) with Guidance software.

Rigaku Corporation
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Website: www.rigaku.com