CAREER: Understanding Ion Transport in Solvated Layered Oxides for Electrochemical Energy Storage

North Carolina State University, Raleigh NC

Investigators

Abstract

Part I: Non-Technical Summary Electrochemical energy storage via batteries and electrochemical capacitors is ubiquitous in modern life, from cell phones and electric vehicles to renewable power grids. Layered metal oxides are an important class of materials for energy storage devices. They reversibly store ions from the electrolyte within the empty spaces found in the interlayer region. This research will explore how tuning the interlayer of these materials by solvation could improve their energy storage properties. The research will lead to improved understanding of fundamental mechanisms of energy storage as well as the design of new layered materials with better energy storage properties. The educational component of this research is motivated by the fact that the rise in global energy use in coming decades will largely come from the electrification of developing countries. The educational plan will train students to collaborate on global challenges across diverse cultures, highlight the societal impact of engineering to recruit and retain under-represented student groups in materials science and engineering, and increase the global diversity of scientists and engineers. The education plan involves collaborations with universities in Uganda, and will use hands-on experiment kits and virtual teamwork to train students to work on diverse teams to tackle global challenges Part 2: Technical Summary Due to their importance for electrochemical energy storage, significant research efforts have been dedicated to improving the electrochemical transport of cations in layered oxides. This proposed research will determine whether the electrochemical transport of monovalent and divalent cations in layered oxides can be improved by modifying the interlayer via solvation. Such structures preserve the volumetric energy density, lifetime, and safety of bulk oxides, while at the same time providing an atomic-level environment that may be beneficial for interfacial charge transfer and solid-state diffusion. The research approach is to utilize layered tungsten and molybdenum oxides because they offer multi-electron and multivalent redox, hydrated polymorphs, and stability in both aqueous and non-aqueous electrolytes. Solvent exchange will be used to synthesize solvated oxides from hydrated layered oxides. The dynamics of interfacial charge transfer and solid-state diffusion will be determined via electrochemical, microscopic, and spectroscopic techniques including in situ methods. Fundamental understanding of the transport of cations in nanoscale, solvated layers of layered oxides will have a broad impact in fields such as materials science, electrochemistry, surface science, and nanofluidics. The education plan leverages and extends the SciBridge project, developed by the PI, to engage U.S. and African university students in educational outreach in the area of renewable energy.