High-energy lithium-sulfur batteries : from theoretical understanding to materials design
Abstract/Contents
- Abstract
- Rechargeable lithium-ion batteries have transformed the world of portable electronics and consumer devices today, but their specific energy and cycle life remain insufficient for many emerging, modern-day applications such as electric vehicles and grid energy storage. Lithium-sulfur (Li-S) batteries represent a very promising technology for these applications because their theoretical specific energy is about 7 times that of lithium-ion batteries today. However, the challenges of S and Li2S cathodes include: (1) the formation of intermediate lithium polysulfide species which dissolve into the electrolyte during cycling and (2) the low electronic conductivity of S and Li2S. Thus, there is an urgent need for novel encapsulation materials and morphologies for these cathodes that can effectively confine the polysulfide species and facilitate electronic conduction. In this thesis, I will present my work on developing high-energy Li-S batteries, from theoretical understanding to materials design. First, I will present results from theoretical ab initio simulations which enable the systematic screening of promising encapsulation materials. Next, I will present four different designs of S and Li2S cathodes. The first design is that of S-TiO2 yolk-shell nanostructures, which uses oxygen-rich TiO2 as the encapsulation material. The novelty of this yolk-shell cathode lies in the precise engineering of internal void space to accommodate the volumetric expansion of S during lithiation, enabling long cycle life of 1,000 cycles to be achieved. The second and third designs: Li2S-graphene oxide and Li2S-polypyrrole composite structures, use oxygen-rich and nitrogen-rich materials respectively to encapsulate fully-lithiated and fully-expanded Li2S cathodes. Using these cathodes, we demonstrate high specific capacity and stable cycling performance over hundreds of cycles. The fourth design: Li2S-TiS2 core-shell nanostructures, uses highly-conductive and sulfur-rich TiS2 as an effective 2D encapsulation material. This cathode not only exhibits high rate capability of 4C (fast charge/discharge in 15 min), but also high areal capacity of 3.0 mAh/cm2, both of which are on par with commercial standards today. These works pave the way for the future development of high-performance and long-lasting rechargeable batteries.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Seh, Zhi Wei | |
|---|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. | |
| Primary advisor | Cui, Yi, 1976- | |
| Thesis advisor | Cui, Yi, 1976- | |
| Thesis advisor | Cui, Bianxiao | |
| Thesis advisor | Melosh, Nicholas A | |
| Advisor | Cui, Bianxiao | |
| Advisor | Melosh, Nicholas A |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Zhi Wei Seh. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Zhi Wei Seh
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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