04/09/2021
By Sokny Long

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a master’s thesis defense by Joseph Egitto on “High Energy Density Redox-Mediated Flow Batteries with a Bio-Inspired Electrolyte.“

Master’s Candidate: Joseph Egitto
Defense Date: Friday, April 23, 2021
Time: 2 to 4 p.m. EST
Location: This will be a virtual defense via Zoom. Those interested in attending should contact Joseph_Egitto@student.uml.edu and committee advisor, Ertan_Agar@uml.edu, at least 24 hours prior to the defense to request access to the meeting.

Committee Chair (Advisor): Ertan Agar, Assistant Professor, Mechanical Engineering Department, University of Massachusetts Lowell

Committee Members:

  • Xinfang Jin, Assistant Professor, Mechanical Engineering Department, University of Massachusetts Lowell
  • Fuqiang Liu, Associate Professor, Mechanical Engineering Department, University of Massachusetts Lowell

Brief Abstract:
The continued use of fossil fuels for electricity generation has led to an increase in greenhouse gas emissions, causing mass-pollution of our atmosphere and detrimental impacts on the environment. Widespread implementation of renewable energy sources can reduce the amount of carbon dioxide and other pollutants typically given off from carbon-based resources, such as coal and oil. The switch to using renewable energies for electricity generation is inevitable, but to do so would require a solution to the unreliable electrical output due to the intermittent nature of these energy sources. A potential solution to allow for a complete carbon-neutral electricity grid would be to implement a grid-scale energy storage system, capable of both short- and long-duration energy storage. Among various energy storage technologies, redox flow batteries (RFBs) are considered as a prime candidate to solve this intermittency issue due to their unique architecture that allows for unprecedented scalability and flexibility required for grid integration. Compared with conventional rechargeable batteries, electrolyte solutions are stored in external tanks, and are pumped into a flow cell where the reduction-oxidation (redox) reactions occur, converting chemical energy into electrical energy. However, compared to Li-ion batteries, the low energy density of RFBs, which is primarily governed by solubility limitations of redox active species dissolved in electrolytes, hinders their utilization for grid-scale energy storage and must be overcome. One such method to overcome the solubility limitation and thus improve the energy density is to utilize solid charge storage materials, which are reversibly oxidized/reduced in the electrolyte tanks upon interaction with the redox active species. These reactions occur without being connected to an external electrical circuit and are herein called ‘indirect redox mediation reactions’.

The primary objective of this thesis is to explore the feasibility of the redox mediation concept for flow battery applications and establish the theoretical basis necessary to enable rational design and development of flow battery systems containing solid charge storage materials. To accomplish this objective, a highly stable bio-inspired electrolyte, vanadium(iv/v)bis-hydroxyiminodiacetate (VBH), is selected as the redox active material. Implementing VBH as a high-stability testbed (i.e., no interference from side reactions) would allow the detailed analysis required for the elucidation of the indirect redox mediation reactions. For the solid charge storage material, cobalt hexacyanoferrate (CoHCF), a Prussian blue analog, is selected based on its formal potential (reported as ~0.32-0.36 V vs SHE, in aprotic solutions), which overlaps well with the formal potential of VBH. In this study, the performance characteristics of the RFBs with and without solid charge storage materials present will be reported and compared using a suite of electrochemical methods, including charge/discharge cycling, polarization curve measurement and cycling voltammetry. Furthermore, operating conditions and key design parameters related to solid charge storage medium in the tanks are elucidated for the realization of the largest improvement in energy capacity.

All interested students and faculty members are invited to attend the online defense via remote access.