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ION SOLVATION, MOBILITY AND ACCESSIBILITY IN IONIC LIQUID ELECTROLYTES FOR ENERGY STORAGE

Huang, Qianwen
http://rave.ohiolink.edu/etdc/view?acc_num=case1554307805686704

Abstract Details

2019, Doctor of Philosophy, Case Western Reserve University, Chemical Engineering.
Ionic liquids (ILs) are salts that consist of only ions and are in a liquid phase at ambient temperature. Their unique properties, including non-flammability, negligible volatility, wide electrochemical stability window, high thermal stability, and structural tunability, enable ILs promising electrolytes for safer energy storage devices, such as lithium-metal batteries. Lithium metal batteries have about ten times higher theoretical energy density than traditional lithium-ion batteries. However, due to the high reactivity of the metallic lithium electrode, dendrites (needle-like electrodeposits) can form during battery charging and discharging. The formation of lithium dendrites can lead to efficiency loss, capacity decay, short circuits and thermal runaway. To address these safety challenges, a promising approach is to replace the carbonate organic electrolyte solvents with ILs. However, the slow lithium ion transport in IL-based electrolytes limits the charging and discharging rates of a rechargeable battery for practical applications. In this research, we developed IL mixtures with decreased viscosity and increased lithium ion mobility. These IL-based electrolytes demonstrate increased stability at room temperature in the Li-LFP cells where lithium metal is the anode and lithium iron phosphate, LiFePO4 (LFP) is the cathode. ILs are also being explored for use in supercapacitors with high power density due to their wide electrochemical window. However, the main challenge of such application is the poor wettability of ILs to porous electrodes. To address this challenge, we investigate a novel hybrid material designed in the form of a capsule with reduced graphene oxide shell and IL core (rGO-IL) that eliminates some of the challenges with wettability. Increased capacitance (based on active material mass, rGO) and surface utilization have been achieved in supercapacitors with the designed rGO-IL capsules. It is recognized that the developed rGO-IL material may have broader scientific impacts such as the CO2 separation processes. A current pressing need in CO2 capture from process exhaust gases or even air is the discovery of materials that have high CO2 capacity and selectivity without kinetic limitations. ILs have high CO2 solubility, however suffer from large viscosities which imposes mass transport challenges for CO2 uptake and separation. An explorative study on the utility of rGO-IL materials for CO2 separation is carried out as a possible future direction for the application of rGO-IL capsules. Preliminary results demonstrate increased CO2 absorption capacity with improved absorption mass transfer rate with GO-IL capsules, compared to bulk ILs.
Burcu Gurkan (Advisor)
Rohan Akolkar (Committee Member)
Robert Savinell (Committee Member)
Ozan Akkus (Committee Member)
240 p.
Chemical Engineering
Ionic liquid, energy storage, lithium batteries, supercapacitors, CO2 capture

Recommended Citations

Citations

  • Huang, Q. (2019). ION SOLVATION, MOBILITY AND ACCESSIBILITY IN IONIC LIQUID ELECTROLYTES FOR ENERGY STORAGE [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1554307805686704

    APA Style (7th edition)

  • Huang, Qianwen. ION SOLVATION, MOBILITY AND ACCESSIBILITY IN IONIC LIQUID ELECTROLYTES FOR ENERGY STORAGE. 2019. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1554307805686704.

    MLA Style (8th edition)

  • Huang, Qianwen. "ION SOLVATION, MOBILITY AND ACCESSIBILITY IN IONIC LIQUID ELECTROLYTES FOR ENERGY STORAGE." Doctoral dissertation, Case Western Reserve University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1554307805686704

    Chicago Manual of Style (17th edition)

case1554307805686704
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© 2019, some rights reserved.Creative Commons License ION SOLVATION, MOBILITY AND ACCESSIBILITY IN IONIC LIQUID ELECTROLYTES FOR ENERGY STORAGE by Qianwen Huang is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.