Investigation and Control of the Electrode/Electrolyte Interface in Electrochemical Systems

Citation

Lee, Brian Chansol (2025) Investigation and Control of the Electrode/Electrolyte Interface in Electrochemical Systems. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/fz2d-pe37. https://resolver.caltech.edu/CaltechTHESIS:03272025-184257192

Abstract

In electrochemical reactions, the electrode/electrolyte interface is of vital importance, as no reactivity occurs in the bulk electrode or the electrolyte. Often, the interface can be the difference between a successful reaction and a failure. In this thesis, we present three works wherein the electrode/electrolyte interface is studied and controlled to drive desired electrochemical reactivity. A Mg-In alloy is employed for Mg metal batteries to prevent Mg dendrite growth, which can cause cell shorting and failure. By coating the surface of Mg metal electrodes with the Mg-In alloy, the nucleation of Mg dendrites is suppressed and instead the Mg electroalloys into the surface alloy upon reduction, significantly increasing the cell life time. Next, the Li-intercalation material LiTiS₂ is studied for use in organic reductive electrosynthesis as counter anodes. Traditional metal sacrificial counter anodes are known to cause issues such as surface passivation, chemical reactivity, and cross-plating at the working electrode, which is deleterious to the desired organic reactivity. It is found that LiTiS₂ surface is less reactive in organic electrolytes, reducing both passivation and chemical reactivity. Further, Li⁺ de-intercalated from LiTiS₂ oxidation is found to be less susceptible to cross-plating than Zn, a common sacrificial anode. Finally, the effect of electrode material on the electrochemical reduction of ᵗBuI is studied. Using electrochemical characterization, it is found that the reduction is catalyzed on Au and Ag through adsorption of the initial substrate, as well as the adsorption of the reactive intermediate tBu radical. The catalysis of ᵗBuI reduction can have meaningful consequences for organic reactivity, driving the desirable generation of the carbanion nucleophile from alkyl halide reactants.

Thesis Files