Energy Storage Science and Technology ›› 2024, Vol. 13 ›› Issue (1): 72-81.doi: 10.19799/j.cnki.2095-4239.2023.0773

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Spatially-resolved neutron diffraction study of the homogeneity of electrochemical reaction in lithium-ion batteries

Wenxin TONG1(), Zhongyuan HUANG1, Rui WANG1, Sihao DENG2, Lunhua HE2,3, Yinguo XIAO1()   

  1. 1.Peking University Shenzhen Graduate School, Shenzhen 518055, Guangdong, China
    2.Spallation Neutron Source Science Center, Dongguan 523803, Guangdong, China
    3.Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2023-10-30 Revised:2023-11-22 Online:2024-01-05 Published:2024-01-22
  • Contact: Yinguo XIAO E-mail:tongwx@stu.pku.edu.cn;y.xiao@pku.edu.cn

Abstract:

The homogeneity of electrochemical reactions in lithium-ion batteries, which are electrochemical devices with complex composition, is influenced by various factors, such as electrode material composition, battery structure, and manufacturing processes. Inhomogeneous electrochemical reactions within the battery can exacerbate failures, thereby affecting electrochemical performance, cycle stability, and safety. Recognizing the irreversible impact of battery disassembly on its chemical properties and structure, this study introduced a nondestructive spatially-resolved time-of-flight neutron diffraction method to investigate the homogeneity of electrochemical reactions in large-scale pouch lithium-ion cells. By collecting and analyzing neutron diffraction data in millimeter-scale areas, this study offers insights into the phase transitions in the graphite negative electrode during lithiation for both fresh and failed cells. Herein, distribution maps of the phase content within the negative electrode in different neutron diffraction regions and the lithium concentration distribution in the negative electrodes were constructed by normalization. Furthermore, by integrating high-precision three-dimensional X-ray CT scans, the influence of various factors on the homogeneity of electrochemical reactions, including current density, electrode thickness, and electrolyte concentration, was analyzed. Spatially-resolved neutron powder diffraction provides a rapid and direct estimation for studying the electrochemical reaction homogeneity of metal-ion batteries of different types, shapes, and sizes. This study provides robust technical support for structural and performance optimization and technical battery improvements.

Key words: spatially-resolved neutron powder diffraction, electrode of Li-ion batteries, lithium distribution, homogeneity of electrochemical reaction

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