Correlation of Oxygen Non-Stoichiometry with Electrochemical Behavior in High-Rate Oxide Anodes: A Combined Experimental and Computational Study

NON-TECHNICAL SUMMARY: This research project investigates how missing oxygen atoms, known as oxygen vacancies, affect the performance of titanium niobium oxide (TiNb2O7), a promising material for fast-charging, next-generation lithium-ion batteries. The goal is to understand how these atomic-scale defects affect the way lithium and oxygen atoms move through the material, and how they impact its ability to store and release energy quickly and reliably. By combining computer simulations with cutting-edge experimental techniques, including advanced synthesis, characterization, and performance testing, the researchers aim to uncover the role of oxygen vacancies in battery behavior. This knowledge supports the development of safer, longer-lasting, and faster-charging batteries, helping to strengthen U.S. leadership in energy innovation. The project also provides hands-on training for students and engages the community through outreach programs that promote interest in science, energy, and materials discovery. TECHNICAL SUMMARY: This project aims to establish a quantitative, fundamental understanding of how oxygen vacancies influence lithium and oxygen diffusion, ionic and electronic conductivity, and interfacial behavior in TiNb2O7, a promising high-rate oxide anode material for next-generation lithium-ion batteries. The research comprises three integrated tasks: (1) atomistic modeling of lithium and oxygen diffusion and electronic structure in oxygen-deficient compositions; (2) synthesis with controlled oxygen vacancy concentrations via spark plasma sintering, followed by structural characterization; and (3) electrochemical evaluation to understand how oxygen vacancy concentration affects anode performance and to establish design guidelines for fast-charging oxide anodes. By coupling computational modeling and experiments in an iterative feedback loop, this project enables predictive tuning of oxygen vacancies to optimize electrochemical performance. The combined approach not only advances the fundamental understanding of defect-property-performance relationships in TiNb2O7 but also provides a broadly applicable strategy for defect engineering in functional oxides, contributing new knowledge at the intersection of materials science, solid-state chemistry, and electrochemical engineering. 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.