In situ method for stress measurements in film-substrate electrodes during electrochemical processes: key role of soften
- PDF / 3,720,635 Bytes
- 17 Pages / 594 x 792 pts Page_size
- 27 Downloads / 153 Views
RESEARCH PAPER
In situ method for stress measurements in film-substrate electrodes during electrochemical processes: key role of softening and stiffening Haimei Xie1 · Yilan Kang1 · Haibin Song1 · Jiangang Guo1 · Qian Zhang1 Received: 11 April 2020 / Revised: 30 June 2020 / Accepted: 18 August 2020 © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Electrode stress is one of the main driving forces of electrochemical degradation, which is directly related to battery cycle life, thus attracting great interest. Herein, we propose an in situ method to measure bilayer stresses in film-substrate electrodes during electrochemical processes. This method consists of two parts: stress models featuring Li-dependent material modulus and in situ deformation measurements, through which electrode bilayer stresses evolution accompanied by Li-dependent material modulus can be quantitatively characterized. As application of the method, typical silicon-composite and carboncomposite film-substrate electrodes are selected for in situ mechanical measurements and experimental analysis is performed. Results show that silicon material and carbon material exhibit significant, continuous softening and stiffening, respectively. In two film-substrate electrodes, electrode material films experience compressive stress and current collector substrates undergo a tensile-to-compressive conversion across the thickness. Besides, moduli and stresses in both electrodes vary nonlinearly with capacity, presenting non-overlapping paths between lithiation and delithiation. Based on experimental data, we further demonstrate the key role of Li-dependent modulus on electrode stresses, finding that silicon material softening decreases and carbon material stiffening increases electrode stresses. The deficiencies of current stress measurement method based on Stoney equation and the applicability of our method are discussed. Keywords In situ measurement · Stress model · Bilayer film-substrate electrodes · Silicon softening · Carbon stiffening · Lithiation–delithiation non-overlapping
1 Introduction It is generally agreed that the lithiation–delithiation behavior of lithium-ion batteries involves an electrochemical–mechanical coupling problem [1–5]. The electrochemical process causes microstructure change and volume expansion of the electrode material; as a result, stress occurs in electrodes. More importantly, stress is a main driving force of battery degradation, causing damage and pulverization in the electrode material, as well as failure and collapse in the electrode structure, which triggers a series of severe consequences, such as poor cycle life, aging, and safety issues
B B 1
Jiangang Guo [email protected] Qian Zhang [email protected] Tianjin Key Laboratory of Modern Engineering Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
[6–9]. Mechanics researchers have focused on overcoming difficulties in achieving in situ experimental me
Data Loading...
