High Energy and High Power Magnesium Batteries

Date

2019-08

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Abstract

Magnesium batteries are emerging as attractive candidates 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 Mg2+ ingression 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. 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 circumvents the intercalation of Mg2+ by using a Na-insertion cathode in a Na+/Mg2+ hybrid electrolyte. However, as a matter of fact that the cathode and anode employed different charge carriers, the cell energy was limited by the concentration of Na+ in the electrolyte. 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 Mg2+-storage chemistry using chloride-free electrolytes. The observed specific energy (243 Wh kg-1), and cycling stability (87%@2500 cycles) of Mg-storage cells consolidated polymers as promising cathodes for Mg batteries. Finally, I reported a quinone molecule, pyrene-4,5,9,10-tetraone (PTO), that can circumvent sluggish Mg2+ diffusion through a dissolution-precipitation reaction, and its intrinsic ion-coordination charge storage mechanism does not involve bond-breaking and bond-formation, therefore demonstrating potential to achieve high power. By coupling PTO cathode with a high-performance electrolyte, Mg(CB11H12)2 in DME/G2, I created an Mg battery with a specific energy of 566 Wh kg-1 and an ultra-high power of 30 kW kg-1, which surpassed all previously reported Mg batteries. I hope that the work described in this dissertation provides an in-depth understanding of the technical challenges of Mg batteries and effective solutions to address them.

Description

Keywords

Magnesium batteries, Batteries, Organic cathodes

Citation

Portions of this document appear in: Dong, Hui, Yifei Li, Yanliang Liang, Guosheng Li, Cheng-Jun Sun, Yang Ren, Yuhao Lu, and Yan Yao. "A magnesium–sodium hybrid battery with high operating voltage." Chemical Communications 52, no. 53 (2016): 8263-8266. And in: Dong, Hui, Yanliang Liang, Oscar Tutusaus, Rana Mohtadi, Ye Zhang, Fang Hao, and Yan Yao. "Directing Mg-Storage Chemistry in Organic Polymers toward High-Energy Mg Batteries." Joule 3, no. 3 (2019): 782-793.