Single-particle electrochemistry to identify fundamental barriers to magnesium ion intercalation in transition metal oxides

University Of Illinois At Chicago, Chicago IL

Investigators

Abstract

Li-ion batteries have seen a steady growth in achievable energy storage capacity and durability over the last several years, rendering them the dominant market player. However, accelerating the transition to a society based on renewable energy still requires new alternative battery chemistries. One possible solution is to replace lithium ions as the primary carriers of electronic charges by multivalent carriers like magnesium. The theoretical gains with the use of magnesium are hampered by the inefficient transport of magnesium within the battery at relevant temperatures of operation, especially in the solid oxide cathodes needed for transformational gains in energy density. In this project, novel approaches of electron microscopy are combined to examine the intrinsic reactivity of model transition metal oxides as cathodes in Mg-ion batteries. These approaches will isolate the behavior of individual electrode particles from the effect of the complex architectures used in conventional electrodes and reveal the balance between productive and competing processes at the atomic scale. This project will quantify critical bottlenecks in the development of high-energy batteries based on magnesium to unlock the next generation of rechargeable devices. The project’s activities center around education and training providing the diverse student body at University of Illinois - Chicago (UIC), a Research-1 Hispanic-serving institution with opportunities for hands-on research and learning experiences in cutting-edge electrochemistry, materials science, and characterization research. The integration of research and education through the training of undergraduate and graduate students in state-of-the-art in-situ scanning transmission electron microscopy and electrochemistry is an integral feature of this project. This research project seeks to identify and overcome the fundamental barriers of efficient Mg-ion intercalation in transition metal oxide cathodes using a combination of cathode synthesis, electrochemistry, and state-of-the-art electron microscopy. Several oxides have now been shown to be active toward Mg intercalation, yet the process demands high temperature and is accompanied by an unacceptably high hysteresis, a fatal flaw for practical application. This project focuses on MgV2O4 as a model system to unravel the fundamental barriers to efficient Mg2+ intercalation by conducting measurements on single particle cathodes, revealing the intrinsic behavior of the material, rather than the convolution of cell design and transport across a complex electrode architecture. Novel in-situ holders, thin-film model system cathodes and scanning transmission electron microscopy provide an atomic-scale description of bulk and interfacial transformations of single particles during electrochemical cycling, separating changes due to reversible intercalation from irreversible competing reactions. The evaluation of reactivity at multiple temperatures will provide unique insight into the kinetic limitations of the structural transitions, charting a path for Mg-based cathodes towards a battery at, or near, room temperature. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.