Composite electrode design for next-generation lithium-sulfur batteries
- Secondary lithium (Li) ion batteries are essential in driving the rapid development of electronic devices. While the rising demand for high performance portable electronics continues to sustain interest in developing more advanced lithium ion (Li-ion) batteries, the emerging applications of grid scale energy storage and electric vehicles are pushing lithium battery research to the next level. To meet the targets for grid storage as well as electric vehicles batteries set by the US Department of Energy (DOE), battery chemistries beyond the current lithium ion systems are highly required. Among all the recently-emerging technologies, lithium sulfur (Li-S) battery is one of the leading candidates that could have high specific energy and low cost. In my thesis, I will very briefly introduce the fundamentals of conventional Li-ion batteries and the next-generation Li-S batteries, compare the different chemistries of conventional lithium-ion batteries with Li-S batteries, and then examine the main challenges and present my study on designing the nanoscale "composite electrode" to address problems from both the lithium metal side and sulfur side. Lithium sulfur battery has a practical energy density of around 600 Wh/kg, about 3 times that of the current lithium ion batteries. Lithium metal anode has long been regarded as the "holy grail" of battery technologies, due to its low potential and high specific capacity. However, the safety hazards and capacity fading problem have prevented lithium metal anode from practical realization. In the first part of this thesis, I will present my research on using various strategies to build a composite Li metal anode. By encapsulating Li inside a three-dimensional porous matrix via melt-infusion, electrochemical deposition and mechanical deformation, we demonstrated the fabrication of such a composite anode. The resulting lithium--matrix composite anode was then subjected to battery cycling and exhibited superior performance compared with bare lithium metal anodes. In the last part of this thesis, I will describe my work on using hydrogen reduced titanium dioxide nanostructures as matrix to improve the sulfur cathode performance. On the cathode side, sulfur and its discharge product are highly insulating. In addition, the intermediate discharge products (lithium polysulfides) can easily dissolve into the electrolyte and shuttle between electrodes, which leads to a fast capacity decay and limited cycle performance. By embedding sulfur in hydrogen reduced titania inverse opal structure, sulfur utilization in the electrode is significantly improved and the polysulfide species are strongly trapped both physically and chemically, resulting in higher specific capacity and longer cycle life. We believe our work will contribute significantly to the energy-related field and also inspire research in other areas.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Materials Science and Engineering.
|Cui, Yi, 1976-
|Cui, Yi, 1976-
|Statement of responsibility
|Submitted to the Department of Materials Science and Engineering.
|Thesis (Ph.D.)--Stanford University, 2018.
- © 2018 by Zheng Liang
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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