Ph.D. candidate Justin Roller, Materials Science and Engineering (MSE) program was awarded a $20,000 graduate fellowship by the CT Space Grant Consortium in November 2011. This competitive program was initiated by NASA in 1989. Space Grant is a national network of colleges and universities working to expand opportunities for Americans to understand and participate in NASA’s aeronautics and space projects by supporting and enhancing science and engineering education, research and public outreach efforts. The goal of the program is to make the United States the Aerospace Leader of our Solar System and the CT Space Grants mission is to make Connecticut the National Leader in NASA-related education, research and workforce development by inspiring students to pursue careers in science, mathematics, engineering and technology, or STEM, as well as curriculum enhancement and faculty development. Justin joined the MSE program under the guidance of Dr. Radenka Maric in August 2010. He holds a MASc in Materials Engineering from the University of British Columbia and an undergraduate in Chemistry from Georgia State University. Prior to joining UConn he worked for the Government of Canada at the Institute for Fuel Cell Innovation in Vancouver. His research interests are in catalysts for clean energy applications and synthesis by flame deposition methods. In addition to the CT Space Grant fellowship he is also a GAANN scholar.
In this project Justin will work under the guidance of Malgorzata Gulbinska at Yardney Technical Products, a Connecticut developer of lithium ion batteries for US space and military clients, to develop lithium ion battery cathode materials in support of NASA’s Science Mission Directorate (SMD). Space exploration requires energy storage devices capable of handling the harsh conditions of space that can also integrate with primary energy harvesting devices (i.e. solar arrays); state-of-the-art lithium ion batteries are best suited to this task as rechargeable (secondary) batteries but still have not realized their full potential in terms of durability, manufacturability and power density. Justin will address these limitations by decreasing both the electrode thickness and cathode particle size through the use of a novel dry and direct one-step deposition of ultra-thin layers (1-2 microns) comprising nanosized mixed nickel cobalt oxide particles onto a rolled aluminum foil with a flame combustion process. The process utilizes an organic liquid that acts as both a solvent for the inexpensive nickel and cobalt precursors and as the fuel to provide the enthalpic heat required for their decomposition into vapors and finally deposition.The aluminum current collector used for the cathode will be protected from the flame and kept below 80 C° via an air quenching mechanism coupled with a secondary non-combusted spray stream containing a carbon conductivity enhancer. Reducing the thickness of the cathode by an order of magnitude, not attainable by current tape casting methods, will facilitate faster Li ion diffusion and reduced ohmic resistance by eliminating unused/inaccessible portions of the cathode while still providing ample storage capacity. The nano dimensional size of the produced cathode particles increases the available surface area of crystallites and thus produces more entry paths for the diffusing Li species. Additionally, shorter diffusional lengths for the lithium-ion travelling from the particle core to the surface of the 10-20 nm nickel cobalt oxide will enhance the power density currently attainable by existing technologies. The nano dimensions of the catalyst will not only facilitate faster Li ion diffusion (higher power density), but will also enable better strain accommodation for volumetric expansion/contraction during charge/discharge to extend the cathode lifetime.