A systematic investigation of cycle number, temperature and electric field strength effects on Si anode. (15th April 2018)

• Record Type: Journal Article
• Authors: Fang, Qihong; Wang, Qiong; Li, Jia; Chen, Eenze; Liu, Bin; Wen, Pihua
• Is Part Of: Materials & design. Volume 144(2018)
• Page Start: 1
• Page End: 13
• Publication Date: 2018-04-15
• Subjects: Silicon electrode -- Cycling number -- Temperature -- Electric field strength -- Molecular dynamics; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2018.02.019
• Languages: English
• ISSNs: 0264-1275

Abstract

Highlights: Deformation behavior and microstructure evolution of Si anode are analyzed by MD simulations. Effects of cycling number, crystal orientation, temperature and electric field strength are explored. Considering surface stress, analytical modeling of diffusion-induced stress is established. Number and radius of nanovoid depend upon cycling number, temperature and electric field strength. Surface morphology of Si electrode relies on cycling number and temperature as well as electric field strength. Graphical abstract: Abstract: Cycling number, crystal orientation, temperature and electric field strength play key roles in affecting the capacity and cycling ability of Li-ion battery. However, the detailed dynamic and continuous process of capacity decline mechanism from above factors need to be further understood at nanoscale. Herein, we report deformation behavior and microstructure evolution of Si anode under electric field using molecular dynamics simulations. The results show larger cycling number and electric field strength cause larger volume expansion of Si electrode, leading to the capacity loss and the reducing cycling ability as well as the decreasing structural stability. The phase transformation from diamond cubic structure to body-centred tetragonal structure and the amorphous formation depend on lithiated and delithiated depths. The crystal orientation [100] Si anode produces the volume expansion owing to a large number of nanoscale void. The various temperatures strongly affect the number and radius of nanovoid. The associated transition in the nanovoid nucleation due to the involuntary diffusion process is driven by larger cycling number or electric field strength, resulting in the irreversible capacity loss of Li-ion battery. An established analytical model suggests that diffusion-induced stress not only relies on the position of Si anode but depends upon the cycling time.