(3cz) Composite Polymer-Ceramic Membranes for Redox Flow Batteries

Redox flow batteries (RFBs) are promising technology for medium and large-scale stationary energy storage. Scalability along with decoupled energy storage capacity from power generating reactor are the major advantages of RFBs¹. While numerous chemistries have been developed over the past 50 years; the state-of-the-art systems utilizing aqueous transition metal salts (e.g., vanadium) as the dissolved charge-storage compounds, are too-expensive for widespread adoption motivating research and development into alternate redox couples and accompanying electrolytes. Non-aqueous chemistries are emerging class of RFBs that leverage the large electrochemical stability windows of organic solvents (> 3 V) and facilitate the use of redox couples with electrode potentials outside of the aqueous electrochemical stability window². Moreover, redox active organic molecules, typically quite soluble in nonaqueous electrolytes, can be tailored via molecular functionalization and mass produced through inexpensive routes. Therefore, NAqRFBs promise higher energy density (increased solubility), increased power density (increased electrochemical stability window), and versatile operating conditions with reduced overall cost (cheaper electroactive materials). In particular, of the use of non-aqueous electrolytes enables access to Li-based negative electrodes that can boost energy density and further reduce the system footprint.

To develop a hybrid NAqRFB with a Li-based negative electrode, it is critical to block the undesired transport of the solvent and electroactive species between the positive and negative electrolytes. The use of a single-ion conducting ceramics as the ion-exchange membrane within the RFB architecture is one approach. Ideally, such a membrane would block exchange of active species and solvent between the two half-cells, conduct Li cations, possess high mechanical and chemical stability, and be amenable to low cost processing.

In this work, we have explored NaSICON-type³ composite polymer‐inorganic membranes for Li-based NAqRFBs. Specifically, we have investigated two different ceramic structures, Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) and Li_1.4Al_0.4Ge_0.2Ti_1.4(PO₄)₃ (LAGTP), blended with polyvinylidene fluoride (PVDF) as the polymeric matrix. We have characterized the performance and durability of the composite membranes using a suite of microscopic and spectroscopic techniques in combination with in-situ and ex-situ electrochemical diagnostics with an overarching goal of assessing the efficacy of single-ion conductors in NAqRFBs. The insights gained through this work will help to establish the foundational scientific knowledge needed to develop the next generation non-aqueous RFB technology for large scale energy storage.

References:

1. 1. Ashraf Gandomi, D. S. Aaron, J. R. Houser, M. C. Daugherty, J. T. Clement, A. M. Pezeshki, T. Y. Ertugrul, D. P. Moseley, and M. M. Mench, Journal of The Electrochemical Society, 165 (5) A970-A1010 (2018).
2. 2. D. Milshtein, J. L. Barton, T. J. Carney, J. A. Kowalski, R. M. Darling, and F. R. Brushett, Journal of The Electrochemical Society, 164 (12), A2487-A2499 (2017).
3. 3. Allcorn, G. Nagasubramanian, H. D. Pratt III, E. Spoerke, and D. Ingersoll, Journal of Power Sources, 378 353-361 (2018).

Research Interests

Increasing demand for energy has necessitated the utilization of energy sources beyond fossil fuels. Sustainable and environmentally friendly energy resources, such as solar, wind, and tidal energy, are of great importance, as they emit reduced (if any) carbon dioxide. However, the supply of energy through these renewable resources is usually unpredictable and intermittent in nature, while the energy demand (frequency and intensity) is equally variable and can significantly change based on the application, often resulting in a mismatch between the two. Therefore, energy storage technologies are essential to mediate between the variable supply and demand of energy. In response to this need, a variety of energy storage technologies (e.g., pumped hydro) are being implemented. Electrochemical energy devices (e.g., secondary batteries and fuel cells) hold the particular advantage of being geographically flexible; they can be implemented at various locations as stationary or portable energy storage/conversion systems. Further, these devices can operate using different energy sources (e.g., hydrogen energy) and can even utilize inexpensive earth-abundant organic materials.

Fascinated with the unique attributes of electrochemical energy storage/conversion devices, throughout my career, I have developed a solid background in design, mathematical modeling, and prototyping different electrochemical energy systems including non-aqueous and aqueous redox flow batteries, lithium-ion batteries, polymer electrolyte membrane fuel cells, microbial fuel cells, and electrochemical sensors. In addition, this pursuit has led me to collaborate with peers on multiple projects funded by the Department of Energy, MIT Energy Initiative, Joint Center for Energy Storage Research (JCESR), Volkswagen, and other companies (e.g., W. L. Gore and Associates). From these extensive studies, I have found that a critical component to the successful operation of these devices is the efficient separation of the low-potential and high-potential electrolytes to prevent internal short circuiting. Commonly, a membrane is used for separating these two sides; however, this technology is lagging other areas of development in many domains (e.g., non-aqueous redox flow batteries). As a result, I see a need to, and am very interested in, improving reactor design and separation strategies to advance the development of electrochemical energy storage/conversation devices (e.g., RFBs). To this end, as an independent researcher, I intend to develop targeted separation strategies. Some of these approaches include developing high-performance and selective composite polymer-ceramic membranes and implementing novel atomic layer deposition techniques for nanocoating these separators with desired attributes. I am also interested to develop advanced diagnostics capable of real-time analysis of the membrane performance. Further, I plan to develop multiscale mathematical models for optimizing the reactor configuration as well as simulating the transport of the electroactive and electro-inactive species through these membranes.

During my PhD at University of Tennessee, I Invented a novel experimental apparatus (IonCrG – short for Ionic Crossover Gauge) for real-time measurement of ionic species transport through the membrane (commonly called crossover) in aqueous redox flow battery architectures. In addition, I developed novel cell design for passive mitigation of vanadium ions and water crossover in all-vanadium redox flow batteries (VRFBs). Going beyond aqueous chemistries, I joined MIT as a postdoctoral associate where I have focused on developing next-generation non-aqueous redox flow batteries (NAqRFBs) equipped with composite polymer-ceramic membranes (further details are provided in the Abstract section).

Given my prior experience in the field and my research interests, I find myself very excited to pursue my career as an independent principal investigator. Throughout these years, I have gained extensive experience working collaboratively yet in a mentorship role with graduate and undergraduate students, achieving deliverable outcomes with both groups. Recently, I have started to collaborate with the International Journal of Hydrogen Energy as an Assistant Subject Editor and contributing author for the International Association for Hydrogen Energy e-newsletter. I believe this will be a great opportunity for establishing a strong connection with the leaders in the field and will be an invaluable experience for developing a good reputation as a future PI.

Teaching Interests

I really enjoy teaching; the opportunity of sharing my knowledge in any subject with the students and seeing them grasp a new concept is extremely fulfilling to me. I get a lot of satisfaction out of motivating the students for learning new materials.

Throughout my career, I have gained extensive teaching experience managing and instructing many mechanical and chemical engineering courses as a sole-course instructor. As an instructor at the University of Tennessee, Knoxville, I organized and instructed multiple courses such as Fluid Mechanics, Heat Transfer, Thermodynamics, and Engineering Mechanics. In these classes, I developed and adhered to the course syllabus, prepared and delivered lectures, and offered and facilitated office hours outside of lectures. I successfully instructed these courses, having been highly ranked by my students for several consecutive semesters and having received excellent scores (> 4.5/5) in the student-filled Quality of Instructor survey. Although this encouraging feedback has been highly motivating, I continually seek to improve the quality of my teaching, as I critically evaluate my performance and integrate student feedback to continuously increase my score and create more engaging classroom environment.

When I joined Massachusetts Institute of Technology as a Postdoctoral Associate, I continued to nurture my teaching skills, in part by successfully completing the Kauffman Teaching Certificate Program (KTCP). This program has been developed at MIT to help graduate students and postdoctoral researchers for improving their teaching skills. Therefore, through participating in the KTCP, I further developed my teaching philosophy and skills by adopting proven teaching practices and learning how to create an inclusive learning environment for the students.

Considering my prior experiences and the set of skills I have developed as an instructor, I am very excited and prepared to teach multiple courses at the graduate and undergraduate levels, including Fluid Mechanics, Engineering Mechanics, Thermodynamics, Separation Process, and Transport Phenomena. I would also like to develop a specialized graduate level course entitled “Electrochemical Energy Storage and Conversion Devices“ that introduces fundamental electrochemistry concepts and applies them to the various electrochemical energy devices being researched in my research group (e.g., fuel cells, redox flow batteries).

For further information regarding my teaching experiences, research contributions, publications, and future vision, please visit my personal website: http://web.mit.edu/ygandomi/www/