Title:

Electroactive Light Metal Nanostructures and Composites: A Roadmap to Atom-Precise Functional Architectures

Abstract:

Electrochemical reactions are inherently heterogeneous and governed by local electric fields. This fundamental idea underpins the challenges in design of metal anodes for batteries and the design of coatings for inhibiting corrosion. For rechargeable batteries, there is great interest in moving beyond lithium-ion towards magnesium-based electrochemical energy systems, driven in large measure by the alleged imperviousness of metallic magnesium to dendrite formation. Mitigating dendrite formation would allow for the use of metal anodes affording much higher capacities than graphite, but this would require plating and stripping processes at the anode to occur consistently over the course of hundreds of cycles. We have explored the electrocrystallization mechanism of magnesium through in situ video microscopy and X-ray tomography coupled with detailed structural characterization and mesoscale modeling, considering the influence of electrolyte concentrations, applied electric field, and the effects of growth-directing ligands. The studies reveal a diverse range of dendritic, aggregated, and even single-crystal products. We have further designed metallic magnesium nanowire and nanotube architectures that have the potential for yielding low-volume-expansion metal anodes. Our work opens the door for development of anode designs that mitigate dendrite growth, which will be essential for continued progression of Mg-based battery technology.

Mitigating distinctive degradation phenomena is critical to the effective utilization of light metals in structural applications. We have developed a modular design approach to nanocomposite coatings that imbue multiple modes of corrosion protection. I will focus on our efforts in the design of magnesium-nanoparticle- and exfoliated-graphite-based nanocomposites that activate sacrificial cathodic protection and path tortuosity mechanisms, respectively. I will conclude by discussing a “frugal innovation” approach to the design of ZnO-based Janus membranes for applications in menstrual health care products.