Thesis
Development of a physics-based mathematical model of microparticle silicon based lithium half cells
Washington State University
Master of Science (MS), Washington State University
DOI:
https://doi.org/10.7273/000004246
Handle:
https://hdl.handle.net/2376/125122
Abstract
Lithium-ion batteries (LIBs) are considered as the most widely used energy storage systems. The energy density of the LIBs can be increased significantly if the graphite in anode can be replaced with silicon (Si) because Si's energy density, 3,579 [mAh/g], is much higher than graphite's, 372 [mAh/g]. However, during the lithiation-delithiation cycle, curves of electrode voltage vs. capacity differ and forms a hysteresis loop. This voltage hysteresis decreases power density of Si-based batteries. In 2013, Wang et al. reported that they made SiMP lithium half cells and ran lithiation-delithiation cycling experiments with different C-rates. They successfully demonstrated a self-healing chemistry of Si in battery applications. Their experiment also showed a voltage hysteresis during the cycling experiment of SiMP half cells. Similar to traditional LIBs, it was observed that the cell capacity decreases as the C-rate increases. In this work, a physics-based electrochemical model of the SiMP half-cell was developed to explain the causes of voltage gap in lithiation and delithiation cycles, and the capacity differences at different C-rates. To develop the model, at first, particular physics such as lithium diffusion, reaction kinetics, thermodynamics, and mechanical stress and strain was selected, and the relevant equations were included in the model. To investigate the influence of hydrostatic stresses on electrochemical reactions in battery electrodes, a modified version of Butler-Volmer (BV) kinetics equation associated with hydrostatic stress was implemented in the model. Besides, Verburgge & Cheng's analytical approach was applied to identify the importance of mechanical stress in the voltage hysteresis of Si-anode batteries in lithiation-delithiation cycles. Then, literature surveys were conducted to get the physical properties required to make the model a physics-based one. The previously reported parameters such as solid diffusivity, exchange current density, Young's modulus, Poisson's ratio, and partial molar volume were found. Finally, the electrochemical model investigated the impact of hydrostatic stress on the output voltage of the SiMP half cells. In addition, the model was used to identify performance limitations. By checking the impact of the key parameters on the voltage curves during battery cycling, the model provided the possible reasons of voltage differences during lithiation and delithiation.
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Details
- Title
- Development of a physics-based mathematical model of microparticle silicon based lithium half cells
- Creators
- Al-Mustasin Abir Hossain
- Contributors
- SUN UNG KIM (Advisor) - Washington State University, Engineering and Computer Science (VANC), School of
- Awarding Institution
- Washington State University
- Academic Unit
- Engineering and Computer Science (VANC), School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900896419101842
- Language
- English
- Resource Type
- Thesis