CAREER: Identifying and Controlling Interfacial and Structural Instabilities in Transition Metal Oxide Cathodes for Na-ion Batteries

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This project is jointly funded by the CBET Electrochemical Systems program and the Established Program to Stimulate Competitive Research (EPSCoR) Program. Increasing energy demand associated with the growing population, environmental concerns, and technological advancements imposes pressure on modern society to utilize renewable energy sources. Sodium (Na)-ion batteries are promising candidates for large-scale/grid-scale energy storage in terms of availability of raw sources, cost reduction and its environmentally benign nature. However, the electrochemical performance of Na-ion batteries suffers from short cycle life and rapid capacity fade due to severe instabilities in the cathode materials. Lack of understanding of instability mechanisms limits the design of novel cathode materials for Na-ion batteries. The research program will generate fundamental knowledge of the underlying governing forces behind the instabilities and deformations in Na-ion cathodes. This knowledge is a potentially transformative concept for other “beyond Li-ion battery” technologies such as K-ion, Mg-ion, and Ca-ion batteries. The overarching educational objective in this CAREER proposal is to facilitate learning the fundamentals of batteries at K-12, undergraduate and graduate student levels as well as increase public knowledge of the fundamentals of battery operations. The educational and outreach activities include developing graphic novels about battery operation mechanisms for K-12 students, providing an educational platform for future K-12 teachers in STEM fields, preparing battery exhibits at a Science Museum, and integrating research outputs into college education. This CAREER proposal addresses the scientific problem related to poor interfacial and structural stabilities of transition metal oxide cathodes in Na-ion batteries. The proposal will focus on transition metal oxides made of earth abundant minerals such as manganese and iron. The goal of the research activities is to identify the impact of transition metals, operation voltage and electrolyte chemistry on chemo-mechanical instabilities in transition metal oxides cathodes. The guiding hypothesis is that intercalation of Na+ ions in transition metal oxide structure inevitably alters the coupled transport-reaction processes, leading to chemo-mechanical instabilities in the surface and structure of the electrode, resulting in rapid capacity fade. The project will examine the coupling between reaction-transport behavior and mechanical deformations in single and binary transition metal oxide cathodes cycled in organic liquid electrolytes. In operando stress / strain measurements will be coupled with chemical and structural characterization techniques to identify the governing force on interfacial and structural deformations.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.