Concentrated aqueous electrolytes have received much attention in recent years due to their high ionic conductivity and electric chemical window that usually exceeds that of the water electrolysis limitation. We present here two projects. In collaboration with a group at Fudan University in China (Fei Wang, Ziyue Li) we have investigated water phosphoric acid solutions ranging in concentration from 1.25 to 16.6 molar being considered for proton-based batteries. Self-diffusion coefficients measured by pulse field gradient NMR as well as spin-lattice time relaxation measurements were determined for ³¹P and ¹H. The results shed light on the observed maximum in conductivity at the 5.9 molar concentration.

In a second project with Oregon State University (Alexis Scida, David Ji) we examine concentrated aqueous lithium chloride solutions from room temperature down to -40 ⁰C using a combination of pulse field gradient diffusion and 1D NMR including ¹H, ⁷Li, ¹⁷O, and ³⁵Cl. In conjunction with Raman Spectroscopy and first-principles MD simulations we find that upon cooling, Li⁺ tends to pair with Cl^- accompanied by ice-like water clusters and strengthening of H^... Cl^- bonding. The results shed light on the enhanced electrochemical stability.