Moving Closer to Engineering Electrical Properties of Soft Matter

Mastering sustainable energy will be one of the defining scientific challenges of the 21st century. The development of electrical energy storage systems is one key to assuring that renewable power is effective and dependable. 

Recent work from a team of Northwestern Engineering researchers could potentially impact the design of next generation grid-scale electrochemical storage.

Led by the McCormick School of Engineering’s Jeffrey Richards, the investigators identified a particular contribution to charge transport in flow battery technologies, and points the direction to yet unrealized opportunities to engineer the electrical properties of soft matter.

“Flow-based energy storage technologies pump electrically active fluids to store renewable electricity for later use,” Richards said. “The key enabling feature of these fluids is their ability to maintain an electrically connected state while under flow, and at the same time retaining high efficiency. Our results provide a framework to design these fluids for this application.”

Richards is an assistant professor of chemical and biological engineering at the McCormick School of Engineering. The research was reported in the paper “Quantifying the Hydrodynamic Contribution to Electrical Transport in Non-Brownian Suspensions,” published July 12 in the Proceedings of the National Academy of Sciences and included work from postdoctoral fellows Han Lin and Noah Cho, and former undergraduate researcher John Zeeman in Richards’s lab.

The investigators used simulations designed to identify the origin of electrical transport in suspensions of semi-conducting and metallic particles. Their work showed clear evidence linking the shear driven microstructural rearrangement of the suspended particles to the electrical diffusion responsible for the transport process, establishing a union between the electrical response and a scaling parameter that is dependent on both the shear rate and the particle volume fraction. 

Building on previous work that uses simultaneous measurements of a material’s response to deformation and its electrical response, this research could set the stage for more developments in electrical energy storage systems.

“There are exciting opportunities that arise from this research including technologies that are used for impact sensing in soft robots and as replacements for optical encoders,” Richards said.

To reach these conclusions, the Northwestern team collaborated with investigators from MIT, including professor James Swan. Swan suddenly passed away in November 2021 during the drafting of the paper.

“He left behind a young family and was a beloved member of our scientific community,” Richards said. “He was an excellent collaborator, and he will be missed.”