Two separate co-author papers have just been published in ACS Macro Letters, one led by Rahul Sujanani, and the other by James Bamford. Rahul’s study investigates the influence of polymers under moderate hydration conditions, far from the well-studied extremes of rigorously dry, and highly swollen. In this we show the changes in conductivity and ion transport as a function of hydration, controlled by a bespoke setup, designed by Phong Ngyuen. This work demonstrates a crossover point in the relationship between hydration and conductivity that is defined by the hydration number of lithium ions. In James’ study, we show that lithium ion transport in a polymer with a pendant imidazole group can be improved by quaternization of the imidazole to imidazolium. This improvement is maintained even after Tg normalisation, and is further punctuated by an inverse-Haven ratio greater than 1.
Nov 1, 2024
In a very busy week, I had the opportunity to present at both the Southern California Users of Magnets (SCUM) meeting, and the American Institute for Chemical Engineers (AIChE) annual meeting. At SCUM 2024, I presented some of the new work from our group using spatially-resolved NMR methods for direct measurements of thermodynamic phenomena, namely partitioning. I demonstrated this capability through measurements of the octanol-water partitioning coefficients of different solutes, in addition to using NMR profilometry to visualise intensity maps of water moving across membranes. At AIChE, I was proposing my research vision as a faculty candidate. AIChE was an excellent opportunity to meet and network with my peers across a range of disciplines, I always cherish attending talks outside of my comfort zone! For anyone I met this week, please stay in touch. I’m always happy to discuss research, especially ways to incorporate NMR spectroscopy into your work!
Oct 5, 2024
A study borne from my PhD work investigates the effects of mass transport and its interplay with electrochemical kinetics for aluminium-organic batteries. The study purports that there are two competing mechanisms in aluminum-quinone batteries, one that exists under high flux of intercalants, and the other under low flux. The mechanisms are dubbed concurrent and sequential, with these names relating to the ordering of the two-step electronic reduction and corresponding charge compensation. The concurrent mechanism occurs when the electrochemical Damköhler number is small (e.g., under high flux or low rates), and is ordered as electronic reduction-complexation-electronic reduction-complexation; the sequential mechanism by comparison occurs under conditions where the Damköhler number is large, and is ordered electronic reduction-electronic reduction-complexation-complexation. The key difference is that the uncompensated semiquinone form (after the first electronic reduction) is reduced at lower discharge potentials than the ionically compensated semiquinone. These mechanisms can be considered like putting on socks and shoes, you can go sock-shoe-sock-shoe (concurrent, small Dael), or sock-sock-shoe-shoe (sequential, large Dael). This study has consequences to any multielectronic organic electrodes, and tests multiple methods to affect Dael, all to the same conclusion.
Jun 20, 2024
An investigation of eutectic electrolyte mixtures for low-temperature aluminium batteries led by Jonah Wang was published today. This work uses a combination of NMR spectroscopy and electrochemical methods to understand the electrolyte speciation and monitor the cycling performance, both for electrodeposition, and also in aluminium-graphite cells. We show operation down to -40 °C in the ternary AlCl3-urea-[EMIm]Cl mixture at a mole ratio of 1.3-0.25-0.75. In addition to supressing the freezing point, the addition of urea to the binary mixture of AlCl3-[EMIm]Cl improves the cost effectiveness of such electrolytes.
May 24, 2024
We just published a fundamental investigation of selenium structure at different length scales and how it affects the electrochemical reactions achieved in aluminium-selenium batteries. To achieve a full 6-electron capacity of selenium electrodes in aluminium batteries, it is imperative that the Se(0) to Se(–II) is attainable as well as the Se(0) to Se(IV) reactions. This paper documents the viability of the selenium to aluminium selenide electrochemical reduction in glassy selenium, which is seldom observed with crystalline trigonal selenium. This paper challenges the naive assumption that aluminium batteries using sulfur and selenium cathodes would operate in the same way. While both are chalcogens, the bonding topologies of elemental selenium and sulfur are quite different in their most stable forms (trigonal Se chains vs. 8-membered S rings) and this leads to differences in their electrochemical performances.
