Research

Current Projects

Lithium Ion Batteries

Energy storage is a key need for vehicle electrification, with the Li-ion battery (LIB) considered as the primary candidate for vehicular energy storage. Increased automobile electrification will require development of battery technologies with improved power density and energy density capabilities while also improving durability. A stronger understanding of microstructure-transport interactions in LIB electrodes will support deterministic nano- and microscale design of battery electrodes to meet these diverse objectives. We are studying the effects of transport and microstructure on LIB performance and reliability using 3D imaging and microstructural modeling. Current efforts include investigation of of high capacity nanostructured anodes and high power nanostructured cathodes.

This work is supported by a 2015 NSF CAREER Award (CBET-1454437) and has received support from an NSF Collaborative Research Grant (CBET-1438683).

Sodium Ion Batteries

The intermittent and diffuse nature of renewable resources predicates the development of cost-effective, large-scale energy storage. Adopting lithium ion batteries as a large-scale grid energy storage technology is likely to place increased pressure on the limited global supply of lithium as several burgeoning markets compete for supply. Electrochemical energy storage based on more earth abundant materials can address this challenge. The sodium ion battery is a promising alternative for cost-effective large-scale grid energy storage, and tin (Sn) based alloys are promising high-capacity electrode materials for these batteries. Through this research, stronger connection is made between the chemical and structural changes due to sodium storage in Sn-based alloys and the resulting performance of the sodium ion battery.

This work is supported by an NSF Collaborative Research Grant (CBET-1804629)

Exergy Analysis of Power, ISRU, and Life Support Systems

Human exploration of space requires the integration of diverse systems including but not limited to power systems, in situ resource utilization (ISRU), and environmental control and life support (ECLS). Many of these complex systems rely on thermal, chemical, and electrochemical devices to supply power and generate habitable crew environments. Exergy analysis quantifies the work potential of system within a local context, whether terrestrial or extraterrestrial. Using exergy as a basis, diverse systems can be analyzed and integrated effectively to support human exploration of space. We have previously applied this method to analyze the ECLS system that sustain the crew inside the International Space Station (ISS). Currently, we are using exergy analysis to understand the performance and trade-offs of power and ISRU systems that will support human exploration of the Moon and beyond.

This work is supported by the NASA Systems Engineering Research Consortium.

Porous Materials for Aerospace Applications

Selected aerospace and propulsion technologies may benefit from the application of porous materials. One such example is the hybrid rocket motor, which combines a solid fuel with a liquid oxidizer to achieve greater throttling capability with reduced system complexity. We are applying X-ray imaging and microstructural analysis to provide a stronger link between porous rocket motor grain geometry, flow characteristics, and burn behavior. Insights gained may provide tools for the design of heterogeneous materials for propulsion and other aerospace applications.

Facilities

Our primary lab facility is the Transport, Reaction, and Energy Conversion Lab at UAH is a 1,500 ft² laboratory (Shelby Center 309). This lab is led by Prof. George Nelson (MAE) and Prof. Yu Lei (ChE) and houses equipment for materials processing and characterization, electrochemical testing, and catalyst testing. This facility supports research on electrochemical and catalytic material systems relevant to sustainable energy.

Materials processing and handling equipment includes a controlled atmosphere glove box and a fume hood for materials handling, two furnaces (1000 °C and 1200 °C), and a vacuum oven for materials processing. A multichannel potentiostat/galvanostat (Bio-Logic) with 5 A boosters is available for electrochemical testing. A 600 W Rigaku Miniflex X-ray Diffraction (XRD) system is available for characterization of powder and thin film materials. The potentiostat/galavnostat and XRD system were purchased with awards from the UAH Research Infrastructure Fund.

With respect to computational modeling and microstructural analysis, we have several desktop workstations that are available for finite element simulations in COMSOL Multiphysics, image processing, and microstructural analysis. These systems include four Dell Precision workstations: T7810 (Dual 8 Core Intel XEON, 2.4 GHz, 64 GB RAM), T5600 (Dual Six Core Intel XEON, 2.0 GHz, 64 GB RAM), a Dell Precision T7500 (Quad Core Intel XEON, 2.8 GHz, 24 GB RAM), T1700 (Quad Core Intel XEON, 3.1 GHz, 8 GB RAM). These workstations employ Nvidia GPUs with CUDA capabilities.

Prior Projects

Solid Oxide Cells

Solid oxide fuel cells (SOFCs) and electrolyzers (SOEs) are high temperature electrochemical energy conversion devices that may be used for power generation and fuel production. A key component of these solid oxide cells is the porous, composite electrode made of an ion conductor and an electron conductor. High temperature operation permits use of carbon tolerant nickel catalyst that permits fuel flexibility. However, rigorous operating conditions, including elevated temperatures and exposure to reducing and oxidizing environments, cause changes in the microstructural geometry and composition of solid oxide cell electrodes. These microstructural changes lead to performance degradation through loss of chemical reaction sites, breakdown of charge conducting networks, increased stress, and cell failure. We are studying the impact of macroscopic solid oxide cell geometry on microstructural evolution within composite electrode materials using analytical, numerical, and experimental methods. It is expected that cell geometry will create reactant and charge distributions that drive localized microstructural evolution in SOE electrodes.

This work was supported by the NASA EPSCoR program through a Research Infrastructure Grant made by the Alabama Space Grant Consortium.

Neutron Imaging of Enyzimatic Electrochemical Cells

Direct conversion of the chemical energy in sugars and alcohols to electrical energy can be achieved by applying naturally occurring enzymes to enhance chemical reactions. This use of enzymes as catalysts provides the opportunity to create bio-compatible and bio-degradable en batteries and fuel cells. While promising, the further implementation of these enzymatic electrochemical cells is challenged by performance degradation during extended operation at high temperatures and low humidity. In this work we are applying neutron radiography and tomography to study the operation of enzymatic batteries. These neutron techniques enable mapping of bio-catalyst ink regions and in real time imaging of aqueous solution during operation.

This work was supported by a UAH New Faculty Research Award.

Thermoelectric Materials

Thermoelectrics provide the capability to convert thermal energy directly to electricity and open several routes to more efficient energy use. The performance of thermoelectric materials may be enhanced by incorporating microstructural features including grain boundaries, porosity, and precipitate phases. Our current work on thermoelectrics focuses on the effects of microstructural geometry on the transport properties that govern thermoelectric device performance. For example, the arrangement of bulk grains and relative properties of distinct phases may impact current flow within the microstructure, affecting bulk electrical resisitivity. Understanding such interactions can lead to tailored structures that improve thermoelectric device performance and reliability.

This work was supported by an ORAU Ralph E. Powe Junior Faculty Enhancement Award.