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    Pseudocapacitive Oxides and Sulfides for High-Performance Electrochemical Energy Storage

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    Name:
    Chuan Xia - Dissertation - Final Draft.pdf
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    5.665Mb
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    Type
    Dissertation
    Authors
    Xia, Chuan cc
    Advisors
    Alshareef, Husam N. cc
    Committee members
    Han, Yu cc
    Zhang, Xixiang cc
    Hu, Liangbing
    Program
    Material Science and Engineering
    KAUST Department
    Physical Science and Engineering (PSE) Division
    Date
    2018-03-22
    Embargo End Date
    2019-04-16
    Permanent link to this record
    http://hdl.handle.net/10754/627480
    
    Metadata
    Show full item record
    Access Restrictions
    At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2019-04-16.
    Abstract
    The intermittent nature of several sustainable energy sources such as solar and wind energy has ignited the demand of electrochemical energy storage devices in the form of batteries and electrochemical capacitors. The future generation of electrochemical capacitors will in large part depend on the use of pseudocapacitive materials in one or both electrodes. Developing pseudocapacitors to have both high energy and power density is crucial for future energy storage systems. This dissertation evaluates two different material systems to achieve high energy density pseudocapacitive energy storage. This research presents the successful preparation and application of ternary NiCo2S4, which is based on the surface redox mechanism, in the area of pseudocapacitive energy storage. Attention has been paid to understanding its basic physical properties which can impact its electrochemical behavior. Well-defined single- and double-shell NiCo2S4 hollow spheres were fabricated for pseudocapacitor applications, showing much improved electrochemical storage performance with good energy and power densities, as well as excellent cycling stability. To overcome the complexity of the preparation methods of NiCo2S4 nanostructures, a one-step approach was developed for the first time. Asymmetric pseudocapacitors using NiCo2S4 as cathode and graphene as anode were also fabricated to extend the operation voltage in aqueous electrolyte, and thus enhance the overall capacity of the cells. Furthermore, high-performance on-chip pseudocapacitive energy storage was demonstrated using NiCo2S4 as electrochemically active materials. This dissertation also involves another material system, intercalation pseudocapacitive VO2 (B), that displays a different charge storage mechanism from NiCo2S4. By constructing high-quality, atomically-thin two-dimensional (2D) VO2 (B) sheets using a general monomer-assisted approach, we demonstrate that a rational design of atomically thin, 2D nanostructures of atypically layered systems can greatly lower the interaction energy and Li+ diffusion barrier, and it can completely suppress the crystal transformation during the charge-discharge process. As a result, we have successfully enabled the kinetically sluggish step to proceed at room temperature. We show that even at charge-discharge rates as fast as 100C (36 s), these 2D electrodes still offer a high capacity of 140 mAh g-1 due to the rapid Li+ ion diffusion in these 2D sheets. These results discussed in this part conclusively show that the ultrathin 2D geometry of atypically layered or non-layered materials could lead to significantly enhanced pseudocapacitive performance.
    Citation
    Xia, C. (2018). Pseudocapacitive Oxides and Sulfides for High-Performance Electrochemical Energy Storage. KAUST Research Repository. https://doi.org/10.25781/KAUST-XI53T
    DOI
    10.25781/KAUST-XI53T
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-XI53T
    Scopus Count
    Collections
    Dissertations; Dissertations; Physical Science and Engineering (PSE) Division; Material Science and Engineering Program

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