We are developing a computational flow dynamics (CFD) model of a novel reactor that utilizes catalyst particles coupled with susceptor particles that generate heat upon radio frequency excitation. This heating method will save significant amounts of energy while achieving the same or better reactant conversion. Through the CFD model, we are able to quickly simulate reactor behavior under different operating parameters, including particle size, radio frequency coil thickness and spacing, and reactor temperature.

We are evaluating the stability of commercial catalyst-coated membranes (CCMs) under potential cycling that simulates the stress put on fuel cells in heavy-duty vehicles. Characterization includes polarization curves, mass-specific catalyst activity, electrochemical surface area quantification, and hydrogen crossover. Through these measurements, we are able to track degradation of the catalyst material, the support material, and the polymer membrane separator.

We have developed a computational flow dynamics (CFD) model to aid the development of component parts for alkaline water electrolyzers. By using an experimentally-validated CFD model, we can gain deep understanding of how processes like oxygen bubble formation and liquid transport affect each other, allowing more precise optimization of electrolyzer components like the porous transport layer and reactant flow fields.

By using images generated through x-ray tomography, we have built a computational flow dynamics (CFD) model that has actual porous transport layer geometries instead of simulated approximations. These real-life geometries provide more detailed insight into how both liquids and gases move through the different pores, which has a significant effect on electrolyzer performance. In addition, we have developed a method that allows us to combine two different porous transport mediums (for instance, a macroporous and microporous layer) into one geometry without the need for an interface in the CFD model. This means that we can accurately simulate the performance of bilayer, trilayer, and many-layer porous transport media without the need to make a physical version, enhancing the rate at which these PTLs can be evaluated and improved on. 

We have shown that polybenzimidazole (PBI) membranes can be used to both directly electrolyze anhydrous hydrogen chloride to hydrogen and chlorine gas—the first time that a fully anhydrous HCl electrolysis process has been demonstrated—and also to replace the current state-of-the-art Nafion® membrane in an aqueous hydrochloric acid electrolyzer. Importantly, the PBI membrane is a “drop-in” replacement, meaning that no part of the electrolyzer needs to be changed. These projects have also demonstrated that PBI membranes can use different acid dopants for proton conductivity without impairment and that PBI membranes exhibit different performance depending on how they are pretreated. For example, soaking a densified PBI membrane in phosphoric acid for 3 hours results in better performance than a densified PBI membrane soaked in the same phosphoric acid for 24 hours.

Publications:

1. Kris Likit-anurak et al., “Fully anhydrous HCl electrolysis using polybenzimidazole membranes.” International Journal of Hydrogen Energy, Volume 47, Issue 63, Pages 26859-26864 (2022).
2. .Kris Likit-anurak et al., “Polybenzimidazole Membranes as Nafion Replacement in Aqueous HCl Electrolyzers.” ACS Applied Energy Materials, Volume 6, Issue 10, Pages 5429-5434 (2023).

Most current production electric vehicles (EVs) contain cells within a battery pack or module in order to maintain electrical conductivity, prevent fatigue due to vibrations, and provide efficient cooling. Modules may contain cooling fins, thermistors, foam separators, and repeating frame elements to hold the cells. As the cells expand and contract during cycling, the stresses generated can cause the materials in the battery module to deform and crack. This fatigue can result in a loss of electrical or thermal contact and therefore, decreased range, reduced battery life or loss of function, or a loss of heat transfer fluid which could result in electrical shorts. Therefore, it is critical to properly design modules and packs to properly account for the volume change inherent in these pouch cells.

Publications:

1. D. J. Pereira, J. W. Weidner, and T. R. Garrick, "The Effect of Volume Change on the Accessible Capacities of Porous Silicon-Graphite Composite Anodes." J. Electrochem. Soc.  Volume 166, issue 6, A1251-A1256 (2019).
2. T. R. Garrick, K. Higa, S. Wu, Y. Dai, X. Huang, V. Srinivasan, and J. W. Weidner, “Modeling Battery Performance Due to Intercalation Driven Volume Change in Porous Electrodes”, J. Electrochem. Soc. 2017 volume 164, issue 11, E3592-E3597 (2017).
3. T. R. Garrick, X. Huang, V. Srinivasan, and J. W. Weidner,”Modeling Volume Change in Dual Insertion Electrodes”, J. Electrochem. Soc. 2017 volume 164, issue 11, E3552-E3558 (2017).
4. T. R. Garrick, K. Kanneganti, X. Huang, and J. W. Weidner, “ Modeling Volume Change due to Intercalation into Porous Electrodes”, Electrochem. Soc. 2014 volume 161, issue 8, E3297-E3301 (2014).

Understanding of the complex electrochemical, transport, and phase-change phenomena in Li-S cells through the mathematical modeling to addressee the current issues and challenges facing Li-S batteries.

Publications:

1. N. Kamyab, J. W. Weidner, R. E. White, Journal of Electrochemical Society, 166 (2), A334-A341 (2019).

To use multidimensional, multiscale, and multiphase polymer electrolyte membrane fuel cell (PEMFC) model to enhance understanding of water transport inside gas diffusion layer (GDL) and microporous layer (MPL) during fuel cell operations. The outcomes will facilitate the development of advanced mass transport design in order to enhance the performance and the operational robustness.

Publications:

1. P. Satjaritanun, S. Hirano, I.V., Zenyuk, J.W. Weidner, N. Tippayawong, "Numerical Study of Electrochemical Kinetics and Mass Transport inside Nano-Structural Catalyst Layer of PEMFC Using Lattice Boltzmann Agglomeration Method," submitted to J. of Electrochemical Society (2019).
2. S. Shimpalee, P. Satjaritanun, S, Hirano, N. Tippayawong, J. W. Weidner, "Multiscale Modeling of PEMFC using Co-Simulation Approach, J. of Electrochemical Society, 166(8), F534-F543 (2019).

The purpose of this work is to use the direct-modeling-based Lattice Boltzmann Method combined with in-situ flow visualization to explore the transport of liquid water inside the gas diffusion layers (GDLs) used in polymer electrolyte fuel cells. The studies include the understanding of water evolution, water saturation, and breakthrough pressure inside the GDL under different conditions and situations that could occur in fuel cells.

Publications:

1. P. Satjaritanun, J. W. Weidner, S. Hirano, Z. Lu, Y. Khunatorn, S. Ogawa, S. Litster, A. D. Shum, I. V. Zenyuk, S. Shimpalee, “Micro-scale Analysis of Liquid Water Breakthrough inside Gas Diffusion Layer for PEMFC using X-ray Computed Tomography and Lattice Boltzmann Method,” J. of Electrochem. Soc., 164(11), E3359-E3371, 2017.
2. P. Satjaritanun, S. Hirano, A. D. Shum, I. V. Zenyuk, A. Z. Weber, J. W. Weidner, and S. Shimpalee, “Fundamental Understanding of Water Movement in Gas Diffusion Layer under Different Arrangements using Combination of Direct Modeling and Experimental Visualization,” J. of Electrochem. Soc., 165(13), F1115-F1126, 2018.  

A polymer electrolyte membrane water electrolyzer (PEMWE) produces hydrogen and oxygen via electrochemical oxidation of water. PEMWEs differ from conventional electrolyzers, which use an aqueous electrolyte such as KOH to conduct ions. 3D models can predict not only the curretn density output at a given cell potential, but also the locations of hotspot caused by two-phase transport. This is important to consider in the design of flow fields and porous transport layers in large, commercial PEMWEs.

The objective of this project is to investigate mass transfer in high temperature molten salt system along with corrosion in the systems. Coupling of non-isothermal experiments with CFD modeling of systems with thermal gradients and natural convection will allow enhanced evaluation of corrosion on samples.

Publications:

1. H-S. Cho, J.W. Van Zee, S. Shimpalee. B. Tavakoli, J.W. Weidner, B. Garcia-Diaz, M. Martinez-Rodriguez, L. Olson, J. Gray, “Dimensionless Analysis for Predicting Fe-Ni-Cr Alloy Corrosion in Molten Salt System for Concentrated Solar Power Systems,” CORROSION, 72(6), 742-760, 2016.
2. B. Tavakoli, J. W. Weidner, B. Garcia-Diaz, M. Martinez-Rodriguez, L. Olson, S. Shimpalee, “Multidimensional Modeling of Nickel Alloy Corrosion inside High Temperature Molten Salt Systems,” J. of Electrochem. Soc., 163(4), C830-C838, 2016.
3. B. Tavakoli, J. W. Weidner, B. Garcia-Diaz, M. Martinez-Rodriguez, L. Olson, S. Shimpalee, “Modeling the Effect of Cathodic Protection on Superalloys inside High Temperature Molten Salt Systems,” J. of Electrochem. Soc., 164 (7), C171-C179, 2017.  

The development and testing of a new catalytic material to decompose sulfuric acid. A novel catalyst preparation technique, developed by USC, uses a combination of: (1) strong electrostatic adsorption (SEA), which permits formation of very small metal particles with a narrow distribution of sizes, and (2) electroless deposition (ED) to produce controlled bimetallic catalysts.  A new laboratory scale decomposition reactor will also be designed and tested. The solar driven Hybrid Sulfur (HyS) cycle will also be modeled, integrating the downselected reactor concept with the other HyS interfaced equipment. A large scale solar driven process configuration will be identified, modeled and optimized to achieve solar efficiencies.

Publications:

1. C. Corgnale, S. Shimpalee, Z. Ma, “Modeling of a direct solar receiver reactor for decomposition of sulfuric acid in thermochemical hydrogen production cycles”, in press Intl J. of Hydrogen Energy, 2019. (https://doi.org/10.1016/j.ijhydene.2019.08.231)
2. C. Corgnale, S. Shimpalee, M.B. Gorensek, P. Satjaritanun, J. W. Weidner, W. A. Summers, “Numerical Modeling of a Bayonet Heat Exchanger-based Reactor for Sulfuric Acid Decomposition in Thermo-Electrochemical Hydrogen Production Processes,” Intl. J. of Hydrogen Energy, 42 (32), 20463-20472, 2017.

This Project is about the effect of the balance of plant contaminations on the fuel cell performance. In this project we are working on the impact of different contamination on the fuel cell performance and trying to develop a mathematical model that can show the effect of different contamination mechanisms on fuel cell performance.

Commercialization of polymer electrolyte membrane fuel cells requires low-cost components, materials and manufacturing processes. Specifically, bipolar plate manufacturing utilizes methods that are slow, expensive, and are inappropriate for some advanced flow field designs. It is desirable that new manufacturing technologies be developed that enable advanced designs at high volume and low cost.

Publications:

1. S. Shimpalee, V. Lilavivat, H. McCrabb, A. Lozano-Morales, J.W. Van Zee, "Understanding the effect of channel tolerances on performance of PEMFCs," Intl. J. of Hydrogen Energy, 36/19, 12512-12523, 2011.
2. S. Shimpalee and V. Lilavivat,” Study of Water Droplet Removal on Etched-Metal Surfaces for Proton Exchange Membrane Fuel Cell Flow Channel,” ASME-Journal of Electrochemical Energy Conversion and Storage, 13, 011003-1 – 011003-7, 2016. 
3. S. Shimpalee, V. Lilavivat, H. McCrabb, J.W. Weidner, Y. Khunatorn, H-K. Lee, and W-K. Lee, “Investigation of Bipolar Plate Materials for Proton Exchange Membrane Fuel Cells,” Intl. Journal of Hydrogen Energy, 41, 13688-13696, 2016. 

The overall objective of this project is to develop a better understanding of transport phenomena in current H2 Air polymer electrolyte membrane fuel cells. Water transport and its role in fuel cell performance is the main focus of this project. The project objectives have been achieved by generating custom materials; membranes, catalyst layers, diffusion media and flow fields and characterizing them ex situ, followed by operation in a fuel cell and modeling of the results.

Publications:

1. V. Lilavivat, S. Shimpalee, J.W. Van Zee, H. Xu, and C.K. Mittlesteadt, “Current Distribution Mapping for PEMFC,” Electrochimica Acta,174,1253–1260, 2015.
2. J.R. Rowlett, V. Lilavivat, A.S. Shaver, Y. Chen, A. Daryaei, H. Xu, C. Mittelsteadt, S. Shimpalee, J.S. Riffle, J. E. McGrath, “Multiblock Poly(arylene ether nitrile) Disulfonated Poly(arylene ether sulfone) Copolymers for Proton Exchange Membranes: Part 2 Electrochemical and H2/Air Fuel Cell Analysis,” Polymer, 122, 296-302, 2017.
3. S. Shimpalee, V. Lilavivat, H. Xu, J. R. Rowlett, C. Mittelsteadt, and J. W. Van Zee, “The Effect of Membrane Properties on Performance and Transports inside Polymer Electrolyte Membrane Fuel Cells,” J. of Electrochem. Soc. 165 (11), F1019-F1026, 2018.  

In this project we want to see the effect of bimetallic electrocatalyst on different metal oxide supports towards methanol electrooxidation reaction.

The objective of this project is to describe polymer electrolyte membrane fuel cell (PEMFC) behavior resulting from changes in the fundamental properties of GDLs. This objective is being accomplished by measuring the GDL properties, including micro and macro porous layers, fuel cell performance under a variety of operating conditions, and by developing a mathematical model.

Publications:

1. M. Martinez, S. Shimpalee, and J. W. Van Zee, “Measurement of MacMullin numbers for PEMFC gas diffusion media," J. of Electrochem. Soc.,156/1, B80-B85, 2009.
2. M. Martinez, S. Shimpalee, and J. W. Van Zee, “Assessing methods and data for pore size distribution of PEM fuel cell gas diffusion media,” J. of Electrochem. Soc., 156/5, B558-B564, 2009.
3. J. Farmer, M. Martinez, S. Shimpalee, B. Duong, S. Seraphin, J.W. Van Zee, "Assessing porosity of PEM fuel cell gas diffusion layers by SEM image analysis," J. of Power Sources, 197C, 1-11, 2011.
4. M. Martinez, S. Shimpalee, T. Cui, B. Duong, S. Seraphin, J.W. Van Zee, "Effect of microporous layer on MacMullin number of carbon paper gas diffusion layer," J. of Power Sources, 207, 91-100, 2012. 
5. S. Shimpalee, V. Lilavivat, H. Xu, C. K. Mittlesteadt, Y. Khunatorn, “Experimental Investigation and Numerical Determination of Custom Gas Diffusion Layers on PEMFC Performance,” Electrochimica Acta, 222,1210-1219, 2016. 

In this project we are study the operation of a twin-cell electrochemical filter for removing carbon monoxide (CO) from reformate hydrogen by periodically adsorbing and then electrochemically oxidizing CO on the electrode. During the adsorption step, the effects of various operating parameters (e.g., feed CO concentration, flow rate, electrode catalyst loading, type of feeder gas, temperature) on CO breakthrough are measured. Finally steady-state filter operation is implemented to decrease the CO concentration from 10,000 to 10 ppm.

We are developing our patented gas-fed SO2-depolarized electrolyzer (SDE) for use in the hybrid-sulfur (HyS) process, the only practical, all-fluid, two-step thermochemical cycle for producing hydrogen on a large scale. We have tested our SDE over a range of operating conditions (e.g., current, temperature, SO2 flow rate) and design variations (e.g., catalyst type and loading, membrane type and thickness). A key insight from our work is that the concentration of sulfuric acid increases with current density, which dehydrates perfluorinated sulfonic acid membranes like Nafion and increases cell resistance. We have recently shown that acid-doped polybenzimidazole (PBI) membranes represent an alternative to Nafion because they do not rely on water for their proton conductivity, and therefore they offer the possibility of operating at high acid concentrations and/or elevated temperatures to minimize voltage losses (e.g., kinetic and ohmic resistances).

Currently, the United States has more than 2,200 sites producing biogas, with high growth potential. DOE estimates nearly 14,000 additional sites can be developed. Together these new biogas systems could produce enough energy to power 3.5 million American homes and reduce emissions equivalent to removing 15.4 million passenger vehicles from the road. Our research is directed at reducing investor risk by enhancing in-situ, on-line monitoring techniques and thereby improving the  chances for long-term process success.

Publications:

1. C. E. Turick, S. Shimpalee, P. Satjaritanun, J. W. Weidner, S. Greenway, “Convenient non-invasive electrochemical techniques to monitor microbial processes: current state and perspectives.” Appl Microbiol Biotechnol (2019). https://doi.org/10.1007/s00253-019-10091-y, 2019.
2. A. L. Martin, P. Satjaritanun, S. Shimpalee, B. A. Devivo, J. W. Weidner, S. Greenway, M. Henson; C. Turick, “In-situ Electrochemical Analysis of Microbial Activity,” AMB Express, 8, 162, 1-10, 2018.

Develop a working model to quantitatively understand particle mixing with Lattice Boltzmann Method (LBM). The main goals of this study are to characterize and compare contra-rotating single shaft impellers to single shaft co-rotating dual impellers.

Publications:

1. P. Satjaritanun, E. Bringley, J.R. Regalbuto, J.A. Regalbuto, J. Register, J.W. Weidner, Y. Khunatorn, and S. Shimpalee, “Experimental and Computational Investigation of Mixing with Contra-Rotating, Baffle-Free Impellers,” J. of Chemical Engineering Research and Design, 130, 63-77, 2018.