Kent J. Griffith, Ph.D.

 

Kent J. Griffith, Ph.D.
Postdoctoral Researcher
Northwestern University
Host: Professor Andreas Stein

Abstract

Understanding Intrinsically Rapid Electrochemical Charge Storage in Complex Inorganic Oxides

Lithium-ion batteries have enabled the portable electronics revolution of the past three decades. Looking to 2050, the sustainable energy transition will critically depend on advanced electrochemical energy storage materials – lithium-ion and beyond – to relieve our dependence on fossil fuels for transportation and grid-scale power. A limitation of conventional battery materials is their relatively slow charging rate, which is on the order of hours. While the discharge/charge rate and capacity can be tuned by varying the composite electrode structure, mixed ion–electron transport within the active electrode particles represents a fundamental chemical limitation.

In this talk, I will describe how mixed-metal crystallographic shear oxides with topologically frustrated polyhedral arrangements and dense μm-scale particle morphologies can rapidly and reversibly intercalate large quantities of lithium. Multielectron redox, buffered volume expansion, in situ self-doping, and extremely fast lithium transport approaching that of a liquid can lead to high energy density and rate performance. Characterisation of these phenomena will be presented with structural and (electro-)chemical insights from operando X-ray diffraction and multi-edge X-ray absorption spectroscopy, high-resolution neutron diffraction, and solid-state nuclear magnetic resonance spectroscopy. The direct measurement of solid-state lithium diffusion coefficients (DLi) with pulsed field gradient NMR demonstrates room temperature DLi values of 10–12–10–13 m2 s–1 in these complex oxides, which is several orders-of-magnitude faster than typical electrode materials and corresponds to a characteristic diffusion length of ~10 μm for a 1 minute charge. Materials and mechanisms that enable long-range lithiation in minutes have implications for high-power, fast-charging devices and for broader approaches to electrode design and material discovery.

Kent Griffith research graphic on rapid electrochemical charge storage

Kent J. Griffith, Ph.D.

Kent J. Griffith, Ph.D. is a solid-state chemist interested in materials to solve global energy challenges. At Northwestern University, he has several projects related to lithium-ion batteries, 'beyond Li' battery chemistries, and thermoelectrics, working jointly with the Department of Chemistry and the Department of Materials Science and Engineering. His research incorporates advanced characterization methods to obtain atomic-level insights on mechanisms of operation and degradation in functional materials, especially high-rate lithium-ion batteries. In the lab, he synthesizes new materials, conducts electrochemistry, and uses tools including solid-state nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction. He also regularly visit particle accelerators and nuclear reactors to perform X-ray spectroscopy (XAS, XANES, EXAFS) and high-resolution X-ray and neutron diffraction. Though primarily an experimentalist, he dives into electronic structure calculations to help guide or explain his research and works closely with theorist collaborators.

Griffith completed his doctorate in chemistry at the University of Cambridge and earned his bachelor's degree in chemistry from Indiana University.

Category
Faculty Search
Start date
Thursday, Jan. 14, 2021, 9:45 a.m.
End date
Thursday, Jan. 14, 2021, 11 a.m.
Location