ChBE Seminar Series: Gary Koenig, U. of Virginia
Design of Particles and Particle-Based Flow Systems for Electrochemical Energy Storage Applications
Lithium-ion batteries have become very successful in the consumer electronics industry; however, improvements are still needed with regards to cost and performance for greater market penetration into larger scale applications such as electric vehicles and stationary energy storage. While much progress has been made historically with regards to materials chemistry for improving battery performance, factors such as the distribution of the active material particles within the battery electrode and optimizing cell geometry also are significant factors.
Our group has focused its efforts on synthesizing battery active material particles with controllable morphologies. We have developed methods to tune the size, shape, and composition of precursor particles that are subsequently converted to battery active material particles. Our ultimate goal is to develop approaches to produce controlled particle morphologies using a variety of battery materials, and thus to design particles suited to a specific electrode processing or cell geometry. In this talk, the recent efforts within our group to control battery morphology and composition will be described, as well as some of our planned battery concepts.
One particular energy storage application we are designing our particles for is flow batteries that rely on solid particles to deliver electrochemical energy.
Conventional flow batteries have relied on transition metals dissolved in acidic aqueous solutions as the redox active species that undergo electrochemical reactions to deliver/store energy. The energy density of these systems is limited by both the solubility of the transition metals in the solvent as well as the electrochemical stability window of the aqueous electrolyte. Recent progress has been made in research on flow batteries that have the electrochemical energy stored in solid particles, as opposed to dissolved transition metals. These solid particles do not have the solubility limitations of the dissolved transition metals because they are already active materials in the solid phase, and through selection of the appropriate chemistry can have potentials that exceed those of the conventional flow battery systems. Unfortunately, most of the explored systems rely on slurries with interconnected conductive additives that provide excellent electrical conductivity but extremely high viscosities which will reduce the overall energy efficiency of the system through parasitic pumping costs. This talk will describe preliminary efforts towards a flow battery system with solid particles that are not within an interconnected slurry, but instead rely on collisions with a current collector to deliver and store electrochemical energy. The coupling between electrochemical and rheological properties within this system results in unique tunability of the properties of the electrolyte fluids. In addition, the electrochemical evaluation of the active material in the absence of other typical battery electrode components provides an opportunity to characterize the active material particles.
Gary Koenig completed his B.S. in Chemical Engineering at The Ohio State University in 2004. He then received a Ph.D. in Chemical Engineering from the University of Wisconsin-Madison in 2009 with advisor Nicholas Abbott. His Ph.D. thesis involved the study of the interactions of colloidal particles in structured solvents. After graduate school, he worked as a Postdoctoral Associate at the Department of Energy’s Argonne National Laboratory in the Chemical Sciences and Engineering Division under the supervision of Dr. Ilias Belharouak in the group of Dr. Khalil Amine. His postdoctoral project was the development of a new lithium-ion battery cathode material with an internal concentration gradient at the particle level. In 2012, Dr. Koenig began his appointment as an Assistant Professor at University of Virginia in the Department of Chemical Engineering. His research group focuses on the synthesis and characterization of lithium-ion battery electrode active materials and the impacts of particle organization on electrode properties.