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<b><u><span style="font-size:20.0pt">Defense Announcement</span></u></b></p>
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<b><span style="font-size:18.0pt">High Energy and High Power Magnesium Batteries</span></b></p>
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<b><span style="font-size:14.0pt">Hui Dong</span></b></p>
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<b><span style="font-size:14.0pt"> </span></b></p>
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<b>Degree: PhD, Materials Engineering</b></p>
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<b>Date: 07/18/2019 Time: 10 am – 12 pm</b></p>
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<b>Location: MREB 320</b></p>
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<b>Committee Chair:</b> Dr. Yan Yao</p>
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<b>Committee Members:</b> Dr. Alamgir Karim</p>
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Dr. Cunjiang Yu</p>
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Dr. T. Randall Lee</p>
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Dr. Xiaonan Shan</p>
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<span style="color:black">Magnesium batteries are emerging as an attractive candidate for energy storage in terms of safety, energy density, and scalability because Mg metal has ideal properties as a battery anode: high volumetric capacity, low redox potential,
dendrite-free plating, and earth-abundant resources. One persistent challenge is the lack of high-performance cathodes, since Mg<sup>2+</sup> ingress into and diffusion within cathodes are kinetically sluggish. The main objective of this dissertation is to
demonstrate new research approaches that could effectively overcome these barriers and eventually lead to high-performance Mg batteries.</span></p>
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<span style="color:black">In this dissertation, I proposed two strategies to achieve this goal, including Mg-Na hybrid batteries and Mg-organic batteries. First, I developed an Mg-Na hybrid battery, which can circumvent the intercalation of Mg<sup>2+</sup>
by using a Na-insertion cathode in a Na<sup>+</sup>/Mg<sup>2+</sup> hybrid electrolyte.
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<span style="color:black">The second strategy was to utilize organic compounds as Mg battery cathodes. I first revealed that previously reported organic cathodes all operated on an MgCl-storage chemistry sustained by a large amount of electrolyte that significantly
reduced cell energy. I then demonstrated Mg batteries featuring an Mg<sup>2+</sup>-storage chemistry using chloride-free electrolytes. The observed specific energy (243 Wh kg<sup>-1</sup>), and cycling stability (87%@2500 cycles) of Mg-storage cells consolidated
polymers as promising cathodes for Mg batteries.</span></p>
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<span style="color:black">Finally, I reported a quinone molecule, pyrene-4,5,9,10-tetraone (PTO), that can circumvent sluggish Mg<sup>2+</sup> diffusion through a dissolution-precipitation reaction, and its intrinsic ion-coordination charge storage mechanism
without involving bond-breaking and bond–formation, making it has potential to achieve high power. By coupling PTO cathode with a high-performance electrolyte, Mg(CB<sub>11</sub>H<sub>12</sub>)<sub>2</sub> in DME/G2, I created an Mg battery with a specific
energy of 563 Wh kg<sup>-1</sup> and an ultra-high power of 30 kW g<sup>-1</sup>.</span><span style="font-family:"Calibri","sans-serif""></span></p>
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