Thesis
Ionic polymer-modified carbon as effective sulfur immobilizers in lithium/sulfur batteries
Washington State University
Master of Science (MS), Washington State University
2016
Handle:
https://hdl.handle.net/2376/102809
Abstract
The combustion of fossil fuel has led to many serious environmental issues such as air pollution, global warming and the energy crisis. In order to meet the increasing demand for clean energy, many advanced energy devices have been developed over recent years. Lithium-sulfur (Li-S) batteries are one of the most promising technologies and have drawn much attention due to the high theoretical specific capacity of elemental sulfur (1,672 mAh g-1) and their high gravimetric energy density (2,600 Wh kg-1). Li-S batteries, however, face three key challenges: the insulating nature of sulfur, a large volume expansion, and a formation and migration between two electrodes (shuttling effect) of dissolved polysulfide species. To solve these problems, three different strategies have been taken in this study. First, sulfur and activated carbon (S/AC) composites were synthesized as cathode materials. The activated carbon with high surface area can significantly enhance the conductivity of sulfur cathode. As such, a capacity of as high as 1,094 mAh/g could be achieved at 167mA/g (corresponding to 0.1C rate: ten hours full discharging/charging, 1C = 1672 mA/g). Second, the effect of ionic polymers on battery cycling performance was investigated. Two ionic polymers, Nafion and poly(diallyl-dimethylammonium) chloride (PDDA), were selected to act as a protective layer. It is found that the electrostatic interaction between ionic polymers and polysulfide ions can effectively suppress the shuttling effect and improve battery cycling performance. Last, new cell configurations were tested by employing a Nafion-coated carbon interlayer. The carbon interlayer placed on top of the cathode can provide enhanced conductivity and enhance cathode capacity. After coated with thin Nafion layer, the porous carbon paper could effectively prolong the cycle life of Li/S batteries. When combined with a Nafion-coated carbon interlayer, S/AC composite electrodes could exhibit good performance with 72% retention of its initial capacity after 50 cycles.
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Details
- Title
- Ionic polymer-modified carbon as effective sulfur immobilizers in lithium/sulfur batteries
- Creators
- Shuo Feng
- Contributors
- Minkyu Song (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525028701842
- Language
- English
- Resource Type
- Thesis