中国物理B ›› 2021, Vol. 30 ›› Issue (1): 16201-.doi: 10.1088/1674-1056/abb30e

• • 上一篇    下一篇

  

  • 收稿日期:2020-07-12 修回日期:2020-08-07 接受日期:2020-08-27 出版日期:2020-12-17 发布日期:2021-01-04

Experimental investigation of electrode cycle performance and electrochemical kinetic performance under stress loading

Zi-Han Liu(刘子涵), Yi-Lan Kang(亢一澜), Hai-Bin Song(宋海滨), Qian Zhang(张茜)†, and Hai-Mei Xie(谢海妹)‡   

  1. Tianjin Key Laboratory of Modern Engineering Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
  • Received:2020-07-12 Revised:2020-08-07 Accepted:2020-08-27 Online:2020-12-17 Published:2021-01-04
  • Contact: Corresponding author. E-mail: zhangqian@tju.edu.cn Corresponding author. E-mail: xiehaimei@tju.edu.cn
  • Supported by:
    Project supported by the Major Program of the National Natural Science Foundation of China (Grant No. 11890680) and the National Natural Science Foundation of China (Grant No. 12022205).

Abstract: Lithium-ion batteries suffer from mechano-electrochemical coupling problems that directly determine the battery life. In this paper, we investigate the electrode electrochemical performance under stress conditions, where seven tensile/compressive stresses are designed and loaded on electrodes, thereby decoupling mechanics and electrochemistry through incremental stress loads. Four types of multi-group electrochemical tests under tensile/compressive stress loading and normal package loading are performed to quantitatively characterize the effects of tensile stress and compressive stress on cycle performance and the kinetic performance of a silicon composite electrode. Experiments show that a tensile stress improves the electrochemical performance of a silicon composite electrode, exhibiting increased specific capacity and capacity retention rate, reduced energy dissipation rate and impedances, enhanced reactivity, accelerated ion/electron migration and diffusion, and reduced polarization. Contrarily, a compressive stress has the opposite effect, inhibiting the electrochemical performance. The stress effect is nonlinear, and a more obvious suppression via compressive stress is observed than an enhancement via tensile stress. For example, a tensile stress of 675 kPa increases diffusion coefficient by 32.5%, while a compressive stress reduces it by 35%. Based on the experimental results, the stress regulation mechanism is analyzed. Tensile stress loads increase the pores of the electrode material microstructure, providing more deformation spaces and ion/electron transport channels. This relieves contact compressive stress, strengthens diffusion/reaction, and reduces the degree of damage and energy dissipation. Thus, the essence of stress enhancement is that it improves and optimizes diffusion, reaction and stress in the microstructure of electrode material as well as their interactions via physical morphology.

Key words: prestress loading, silicon composite electrode, tensile stress enhancement, compressive stress suppression

中图分类号:  (Mechanical properties of solids)

  • 62.20.-x
82.47.Aa (Lithium-ion batteries) 46.80.+j (Measurement methods and techniques in continuum mechanics of solids) 65.40.gk (Electrochemical properties)