Description:

Jeffrey J. Richards

Title:
Colloidal Fluids as Electrical Current Collectors

Advances in synthetic techniques have enabled a revolution in the design of colloidal dispersions that contain particles with an enormous variety of sizes, shapes and compositions. These advances have not only provided access to a sophisticated understanding of intimate link between a dispersion’s microstructure and its macroscopic properties, but also form the basis of a powerful design paradigm to formulate advanced colloidal materials to address a wide range of important societal problems.

In this talk, I will highlight our recent progress toward understanding the intrinsic link between the electrical conductivity and the rheological properties of suspensions of electrochemically active nanoparticles. Such suspensions increasingly comprise the working fluid in electrochemical flow applications. In this context, a key design constraint collector is the trade-off between electrical performance and viscosity. To examine the origin of these macroscopic properties, we formulated suspensions of two, high-structured carbon blacks in neat propylene carbonate and characterize their rheological and electrical properties using small amplitude oscillatory shear and impedance spectroscopy at concentrations spanning the fluid-gel transition. Using these methods, we identify the electrical and mechanical percolation transitions and rationalize these results in the context of the equilibrium microstructure determined from scattering measurements. These results coupled with emerging in situ characterization techniques reveal a pathway toward current collectors with improved performance.

Bio:
Jeffrey J. Richards received his PhD in August 2014 from the Department of Chemical Engineering at the University of Washington working for Dr. Lilo D. Pozzo. During that time, he was an NSF IGERT Fellow and the College of Engineering Dean’s Fellow. After graduating from UW, he had the opportunity to join Dr. Norman Wagner’s group at the University of Delaware as a postdoctoral scholar in the Department of Biomolecular and Chemical Engineering Department before starting his NRC Fellowship at the NIST Center for Neutron Research in Gaithersburg, MD. Jeffrey’s current research focus at the NCNR is the development of in situ characterization techniques for electrochemically active colloidal systems.