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Study of Novel Graphene Structures for Energy Storage Applications

Zhang, Lu
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479823012280305

Abstract Details

2016, PhD, University of Cincinnati, Engineering and Applied Science: Materials Science.
Electrochemical energy storage systems (ESSs) such as supercapacitors (SCs) and secondary batteries have attracted significant research interests due to the recent advances in renewable energy techniques, electric vehicles and consumer electronics. Even though ESSs are quiet different in terms of their working mechanism, they share some drawbacks such as unsatisfied production cost, insufficient energy and power density, and lack of multi-functionalities. Those universal challenges in both SCs and batteries have been addressed by the work that is described in the current dissertation. In the study of materials development, a rational design of seamless 3D graphene structure was proposed using chemical vapor deposition (CVD). The novel 3D graphene shows outstanding electrical and good mechanical as well as electrochemical properties with well-controlled mesoporous structure and high electrical conductivity (148 S/cm). These qualities along with the high flexibility of 3D graphene offer a great potential in flexible energy storage applications. Reduction the manufacturing cost has been studied by combing catalyst particles with polymer binders that enables a continuous synthesis of 3D graphene. To address the insufficient energy and power densities of conventional SCs and batteries, the 3D graphene was used as electrode materials. Different chemical treatments such as surface functionalizations and coatings using different electrolyte systems have been also explored. For example, we studied the obtained 3D graphene structure as a scaffold for pseudocapacitive materials such as manganese oxide (MnO2). After electrochemical coating with MnO2, the 3D graphene/MnO2 electrode showed a specific and volumetric capacitance up to 415 F g-1 and 235 F cm-3 respectively, with capacitance retention of 90% after 5000 charge-discharge cycles. Moreover, when a 3D graphene/MnO2 electrode was assembled with a 3D graphene/polypyrrole (Ppy) electrode, the obtained full cell demonstrated a good electrochemical performance with a maximum energy density of 22.3 Wh/kg, a maximum power density of 16.4 kW/kg, and a reasonable cycle life for practical applications. 3D graphene was also used as electrode scaffold for sulfur as well as a current collector to develop the cathode for lithium-sulfur battery. A high capacity of ~ 1000 mAh/g at 0.1 C as well as an excellent rate performance were achieved by a successful encapsulation of sulfur particles with 3D graphene. A flexible in-plane micro-supercapacitor (MSC) was developed using 3D graphene as an active electrode materials followed by laser processing. The 3D graphene MSC showed an excellent areal energy and power densities that could be further improved by using ionic liquid as electrolyte. The 3D graphene MSC also exhibited good mechanical integrity with no obvious capacitance lose even after 5000 bending cycles. Overall, the work presented by this dissertation successfully addressed several critical issues facing the electrochemical energy storage systems such as SCs and Li-S batteries. This study highlights approaches for rational structure design that can be used in development of next generation energy storage systems with high energy and power densities, excellent cyclic life, good reliability and multi-functionalities. Finally, the electromagnetic interference (EMI) shielding behavior of the 3D graphene has been explored and reported here.
Vesselin Shanov, Ph.D. (Committee Chair)
Gregory Beaucage, Ph.D. (Committee Member)
Relva Buchanan, Sc.D. (Committee Member)
William Heineman, Ph.D. (Committee Member)
131 p.
Materials Science
Graphene; Three-dimensional; Supercapacitor; Microsupercapacitor; Lithium-sulfur Batteries; Chemical Vapor Deposition

Recommended Citations

Citations

  • Zhang, L. (2016). Study of Novel Graphene Structures for Energy Storage Applications [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479823012280305

    APA Style (7th edition)

  • Zhang, Lu. Study of Novel Graphene Structures for Energy Storage Applications. 2016. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479823012280305.

    MLA Style (8th edition)

  • Zhang, Lu. "Study of Novel Graphene Structures for Energy Storage Applications." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479823012280305

    Chicago Manual of Style (17th edition)

ucin1479823012280305
248
© 2016, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.