CAREER: Understanding Intermediate Sulfur Phases for Enhanced Energy Storage

About This Grant

Sulfur is an attractive material for energy storage because it is abundant, inexpensive, and can store more energy than materials used in batteries today. Still, sulfur-based batteries have not reached their full potential. The various forms sulfur takes during operations are not well understood. This project focuses on a newly discovered liquid sulfur phase. This liquid form of sulfur has not been explored even though it may be a transformative energy material. The project will investigate how different sulfur phases form, transform, and interact with electrodes during charging and discharging. The team will design sulfur-based electrochemical cells that deliver high energy density quickly and efficiently. The project will lead to a better understanding of sulfur phases and pave the way for low-cost, high-performance sulfur-based energy storage systems. The project will establish a Microscopy, Spectroscopy, and Electrochemical Characterizations (MSEC) program for OU students and the local automotive industry. This project will provide undergraduate research opportunities in the Engineering Chemistry program, introduce K–12 students and teachers to energy science and engineering concepts, and inspire the next generation of scientists and engineers. Sulfur is a highly promising cathode material due to its abundance, low cost, and exceptionally high theoretical capacity. However, the behavior of sulfur during battery operations — especially its phases and transitions, which govern electrochemical performance — is poorly understood. This project highlights a liquid sulfur phase at room temperature, a newly discovered, largely unexplored, and potentially transformative energy material system. The project comprises four objectives: (1) Understand intermediate sulfur phases using in situ and operando platforms; (2) Chemically generate liquid sulfur on carbon electrodes using redox mediators; (3) Electrochemically generate liquid sulfur on carbon electrodes via fast and pulse charging; and (4) Design liquid-sulfur electrochemical cells with high capacity and fast kinetics. The project will employ in situ and operando platforms that integrate customized electrochemical cells, as well as optical, Raman, X-ray, and electrochemical microscopy and spectroscopy, along with a high-speed camera and microelectrodes. The research will close key knowledge gaps in sulfur phases and transitions, leading to the design of high-performance, low-cost sulfur-based electrochemical systems. 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.