ABSTRACT: Arguably, electric and hybrid electric vehicles are the new frontiers for lithium batteries. As a new market it is distinctly different from mass produced microelectronics, not only in the energy per battery unit but also in the power performance requirements. Especially the required charging rates during deceleration and emergency charging, as well as, the discharge rates during startup from standstill are exciting challenges. Consequently new chemistry and new material morphologies like nanowires, shape controlled nanoparticle and size/shape controlled meso-scale agglomerates are being developed at an impressive rate.
The standard methodology to characterize the rate performance of these new materials is to fabricate composite electrodes that combine the electroactive materials with a conductive matrix and polymer binder. This porous electrode structure is filled with electrolyte and thus electron and electrolyte transfer paths to the active material is established. This brings about an important question inherent to the composite electrode, i.e. is the electrochemical performance limited by the active material or by the transport of electrons and/or ions in the electrolyte filled electrode structure?
We have in responds to this type of question developed a series of analytical techniques that allow for the study of the redox reaction kinetics without the use of composite electrodes. These include both in situ and ex situ detection schemes, as well as, several different redox systems appropriate for different positive electrode materials. A major advantage of our approach is that the reaction uniformity throughout the sample provides new kinetic insight, which can help to distinguish between possible reaction mechanisms, thus providing better fundamental understanding of both new and existing redox chemistries.
Bio-sketch: Prof. Steen B. Schougaard, is the professor of Inorganic Chemistry at the Université du Québec à Montréal. A native of Denmark he received this M.Sc degree from the University of Copenhagen, before attending the Chemistry Ph.D. program of the University of Texas at Austin. This was followed by a Postdoctoral Fellowship with Prof. Goodenough also at UT-Austin, and a staff researcher position at RISØ Danish national laboratory. At the Université du Québec à Montréal he has developed in close collaboration with industry a research program around lithium-ion batteries, which include atomistic to mesoscale modeling, advanced in situ characterization and conducting polymer composites.