Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (11): 3538-3544.doi: 10.19799/j.cnki.2095-4239.2023.0503

• Energy Storage Test: Methods and Evaluation • Previous Articles     Next Articles

Study on impedance of lithium-ion batteries with lithium iron phosphate and graphite system under low temperature

Meng LI(), Yue WANG, Jingyi QIU, Yuehua WEN, Zhenwei ZHU, Wenjie MENG   

  1. Research Institute of Chemical Defense, Academy of Military Science, Beijing 100191, China
  • Received:2023-07-24 Revised:2023-08-07 Online:2023-11-05 Published:2023-11-16
  • Contact: Meng LI E-mail:limengfighting@163.com

Abstract:

Lithium-ion batteries are widely used in military and civilian fields because of their advantages, such as high power density, high energy density, and long cycle life. However, the performance of lithium-ion batteries is significantly degraded at low temperatures, which hinders their application in extreme environments, such as polar regions, plateaus, and space. In this study, the discharge performance of the battery at different temperatures (-20~25 ℃) was studied using a soft-packed three-electrode device. Along with being combined with electrochemical impedance spectroscopy, the discharge behavior and impedance characteristics of the positive and negative electrodes of the battery were independently studied under low-temperature conditions. The main limiting factors restricting the low-temperature performance of the battery were analyzed, and strategies for further improving the low-temperature performance of the battery were provided. Studies have shown that the charge-transfer impedance of the negative electrode is the primary source of the impedance of the entire battery, and its electrode polarization is the leading cause of battery polarization. However, with a decrease in temperature, the contribution of the positive electrode polarization to the battery polarization increases. When the temperature drops below -10 ℃, the positive electrode becomes the main limiting factor for the low-temperature performance of the battery.

Key words: lithium-ion batteries, lithium iron phosphate-graphite system, limiting factors of low temperature discharge performance, three electrodes, electrochemical impedance

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