CAREER: Understanding Chemical, Structural and Redox Properties of Disordered Metal Oxides

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Non-Technical SummaryThis CAREER project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, advances fundamental insights into eventually designing higher energy, higher power, and more stable rechargeable batteries to meet the demand of the rapid-growing electric vehicle and energy storage market. Energy storage is a vital technology to enable the widespread adoption of renewable energy and to accelerate the technological advancement towards negative CO2 emission. The Li ion battery technology represents one of the most important energy storage technologies. Further development of Li ion batteries calls for more fundamental studies that can reveal reaction mechanisms and inform the design of new materials. Despite many years of materials development, most commercial Li-ion batteries still rely on several cathode materials that are derived from intercalation materials discovered in the 1980s. In these conventional materials, there are defined pathways for Li ions to transport. Recently, there have been exciting discoveries in new battery materials with disordered Li ion transport pathways. Unfortunately, these materials exhibit inferior battery performance compared to conventional materials, although theoretically they should provide much higher capacity. This project uses advanced experimental methods to develop fundamental understanding of electrochemical processes in these new disordered materials. The successful outcome of this project will establish a knowledge base for further improving these materials. This project also seamlessly integrates research with educating the future workforce for the United States. It provides learning opportunities for elementary students with dyslexia in Southwest Virginia. Dyslexic students, an underrepresented group in STEM fields, can be enormous intellectual assets as history, for example in the field of battery research, has taught us. Separately from this effort, the CAREER project also establishes a sustainable educational program between Virginia Tech and national labs, allowing undergraduate students to perform research in national labs. Overall, through this CAREER project Prof. Lin educates several underrepresented minority students, helping them to excel at performing scientific research and to become future leaders in the energy storage field.Technical SummaryThis CAREER project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, investigates the structure-property relationship for an emerging family of advanced battery materials. The hypothesis underlying the various research objectives of this project is that Li-rich disordered rocksalt oxides, with a globally disordered Li percolating network and combined cationic/anionic redox activities, can potentially increase battery energy density far beyond what is delivered by conventional layered cathodes. However, so far their irreversible chemical and structural transformations during electrochemical cycling have impeded their practical applications. Prof. Lin and his research group carry out holistic fundamental studies to understand how the chemical, structural, and redox properties transform at multiple length and time scales, during materials synthesis and under electrochemical operating conditions in order to resolve these daunting challenges. The project employs experimental methods, including synchrotron X-ray techniques and electrochemical diagnostics, to accomplish the following objectives: (1) probing and controlling the evolution of local coordination environment and global average phase during mechanosynthesis, (2) investigating the redox chemistry as a function of chemical composition, local coordination environment, global phase characteristics, and electrochemistry, and (3) quantifying the multiscale evolution of local coordination environment, global average phase, and redox chemistry upon prolonged electrochemical cycling. Taken together, results from these studies provide mechanistic insights into and advance the electrochemistry of disordered rocksalt oxide.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.