The Effect of Structural Water on Proton and Magnesium Intercalation into Tungsten Oxides
The most common approach for improving the kinetics of energy storage materials has been to decrease the diffusion distance by nanostructuring. Here, we explore a different method by investigating the effects of structural water in bulk crystalline tungsten oxides. In theory, such materials can offer improved charge transfer at the interface and fast ion transport in the bulk during electrochemical energy storage. Hydrated tungsten oxides are model materials for the systematic investigation of the effect of structural water for high power energy storage because of their stability in acidic and non-aqueous electrolytes, reversible redox, and multiple hydrated phases. Our results show that hydrated tungsten oxide exhibits surface-limited (pseudocapacitive) kinetics for proton intercalation even with high mass loadings and large crystallite sizes, which leads to high power capability. On the other hand, the anhydrous tungsten oxide exhibits primarily semi-infinite diffusion-controlled kinetics, typical of battery materials. Our results on magnesium storage into tungsten oxides show that these materials can store multivalent cations via an intercalation-type reaction, and the type of structural water present in the oxide determines its stability. This research identifies the use of interlayer structural water as a viable approach for improving the kinetics of energy storage in layered oxides, as well as the stability of different types of structural water in non-aqueous electrolytes.
Veronica Augustyn, Dept. of Materials Science & Engineering, North Carolina State University
Veronica Augustyn is an Assistant Professor of Materials Science & Engineering at North Carolina State University. From 2013 - 2015, she was a Postdoctoral Fellow at the Texas Materials Institute at the University of Texas at Austin. She received her Ph.D. in 2013 from the University of California, Los Angeles and her B.S. in 2007 at the University of Arizona, both in Materials Science & Engineering. Her research is focused on the development and characterization of materials for electrochemical energy technologies including batteries, electrochemical capacitors, electrolyzers, and fuel cells. In particular, she is interested in the relationships between material structure and morphology and the resulting redox behavior and electrochemical mechanisms. She also leads an award-winning international project at NC State, SciBridge, which develops renewable energy research and education collaborations between universities in Africa and the U.S. She is the recipient of a 2017 NSF CAREER Award and a 2016 Ralph E. Powe Junior Faculty Engagement Award, and is a Scialog Fellow in Advanced Energy Storage from the Research Corporation for Science Advancement.
Publication: Nature Materials, Advanced Energy Materials, Advanced Materials, ACS Nano