Dissertations, Theses, and Capstone Projects

Date of Degree

6-2025

Document Type

Dissertation

Degree Name

Ph.D.

Program

Chemistry

Advisor

George John

Advisor

Robert J. Messinger

Committee Members

Alan Lyons

Mark Biscoe

Subject Categories

Analytical Chemistry | Materials Chemistry | Organic Chemistry | Other Chemical Engineering

Keywords

Aluminum-batteries, Lithium-batteries, Organic Electrodes, Synthesis, Material Design, Spectroscopic and Electrochemical Analysis, Capacity Fading, Electrochemical Transport

Abstract

Using environmentally friendly electrode materials in batteries will reduce greenhouse gases emission and improve issues with global warming. Electrochemically active bio-derived molecules are viable electrode materials that are sustainable, renewable, abundant and easily tuned. However, batteries fabricated from organic materials have poorly understood redox properties, rapid capacity fading, and produce low voltages. These challenges, consequentially, yield batteries with low energy densities, and short cycling lifetime. This work provides solutions to these challenges by synthetically tuning molecular structure to design batteries. Further, a combination of spectroscopy and electrochemical methods were used to elucidate molecular level reaction mechanism which provides systematic pathways to design energy dense organic batteries.

The poorly understood redox properties in organic materials arise from the understudied kinetic, thermodynamic and mass transport variables dictating the electrochemical reaction pathways of organic batteries. Using the aluminum (Al)-anthraquinone battery, we demonstrated that electrochemical mass transport limitations dictate the concurrent or sequential reaction pathway to afford one or two reduction plateaus, respectively. The evolution of a single or double reduction plateau dictates the energy-density of the cell. Hence, an understanding of the variables controlling their occurrence directs the design of high energy-producing organic batteries.

Rapid capacity fading in organic batteries is associated with the dissolution of active material in the solution-based electrolyte. The rapidly fading capacity affects the overall cycling lifetime of the organic battery. We have addressed the capacity fading issue by designing a macro-molecular material, oxygen bridged tetrakislawsone (OBTKL), from henna leaves extract that is insoluble in organic solvents. The naphthoquinone-based molecule achieves good cycling stability with 0.035% capacity fade per cycle for at least 1000 cycles in lithium battery. Further, tests with Al-OBTKL demonstrate that electrochemical self-discharge from the spontaneous interaction between organic electrodes and the electrolyte ions is another cause of rapid capacity fading. Our findings are directional to improve the long cycling life of organic batteries.

Voltage in batteries is a thermodynamic property arising from the potential at which electrochemical redox reactions occur in the battery. We used structural design including the use of the sulfonamide functional group and substituent heteroatoms in OBTKL for high voltage aluminum batteries. The Al-OBTKL cell achieves 1.5 V vs. Al/Al(III) the highest in Al-quinone batteries thus far. Also, Al and sulfonamide based electrodes demonstrated the highest voltage (1.9 V vs. Al/Al(III)) ever to be reported in the field of Al-organic batteries.

Overall, we contribute valuable insights into the design, and fabrication of organic batteries for energy dense storage materials for variable applications. Insights into the mechanisms and structural effects on electrochemical properties guide the design of energy dense batteries. This guidance is imperative to audiences in synthesis, electrochemistry, and chemical engineering aiming to infuse sustainability in energy storage at the commercial front.

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