RESEARCH
Our research is primarily concerned with investigating the interplay between interfacial charge transfer and bulk phase transformation processes in electrochemical devices and is oriented toward the rational design of low-cost, high power and long-lived systems.
Key emphases in this regard include in situ tracking of species transport and mesocrystallization, manipulating electrode surface and electrolyte chemistry/electronic structure to tune the kinetics of electron transfer and developing non-invasive methods to map out decomposition pathways in operating batteries. Primary areas of interest include (both liquid and solid-state) lithium-ion, metal-air (e.g. lithium/sodium-oxygen), and redox-flow energy storage and conversion systems - but may extend to applications in carbon capture, materials synthesis, and thermal energy storage. We make extensive use of a wide variety of electroanalytical, spectroscopic, microscopic experimental tools in close concert with atomistic calculations, as well as statistical modeling and information theoretic methods.
Solid Phases in Conversion Batteries. Phase transformations occur in several energy storage and conversion systems which are promising ingredients in the mix of options needed for a more carbon-free energy economy. Conversion batteries featuring alkali metal-oxygen or metal-sulfur reactions are particularly interesting examples of such systems, as they theoretically can deliver specific energy densities 2 - 3 times greater than state-of-the-art intercalation-based lithium-ion systems. However, much remains to be fundamentally understood about the morphological changes and mechanisms involved in the growth and dissolution of solid phases during electrochemical cycling. In-depth understanding of these processes has the potential to bridge the gap between device-level battery performance metrics (rate capability, cycle life, energy density) and atomic-scale interactions among redox-active species and electrified interfaces. Our specific aims under this topic include in situ experimental investigation and modeling of electrochemically induced crystallization and interfacial and electrolyte engineering for high-energy-density systems.
Understanding Electrocatalytic and Decomposition Mechanisms. Understanding the energetics and reactivity of intermediate species formed during electrochemical device operation is crucial for the development of battery configurations with high rate capability and mutual chemical stability of inner components, and thus, long cycle life. This is a particularly pressing urgency for several next-generation energy conversion systems, where soluble growth/reaction intermediates can react with putatively inert components, such as the electrode substrate or electrolyte. Motivated by the urgency of this challenge for practical, scalable energy storage and conversion, we seek to (a) map out and circumvent decomposition pathways and (b) elucidate the energetics of intermediate species in order to promote fast interfacial charge transfer kinetics in next-generation batteries.
Photoelectrochemistry for Energy Storage and Gas Separation. The combination of redox activity with light absorption (e.g. via light-sensitive small molecules or semiconductors) is emerging as a highly flexible and modular platform for enhancing a wide variety of technologies, spanning molecular electronics, photon upconversion in solar cells and electrolyzers. Our research in this area is focused on the use of small, redox-active molecules in efficient CO2 separation and photo-accelerated fast charging of batteries.