Shining new light on old problems in lithium ion batteries
Binghamton University, State University of New York
Improving the energy storage and release of lithium ion battery is largely limited to the cathode (positive electrode). Commercial high capacity LIBs employ Ni-rich layered oxides (derived from LiCoO2) as cathodes. In these systems, the reversible energy storage capacity is limited to 1 Li+ per transition metal (i.e. Co3+/4+ redox couple). However, only 2/3 of Li+ per redox couple are typically intercalated due to capacity retention issues with fast cycling and high voltages. One approach to increase energy storage and release is to employ multi-electron cathodes that can reversible accommodate more than 1 Li per redox center. Vanadium pentoxide (V2O5) was first proposed in 1976 as a Li-ion cathode, due to its structural easily accommodate Li sites (up to 5 per redox center), multiple redox couples, and the strong enthalpic driving forces for Li-ion insertion within this structure. However, despite these promising attributes, the poor high-rate performance of these materials and issues with retention of capacity over prolonged cycling have limited the widespread commercial development of this material.
In this talk, I will discuss our use of Synchrotron-based x-ray techniques combined with density functional theory to study the evolution of various nanoscale engineered V2O5 (e.g. nanocrystals and aerogels) upon Li insertion and extraction to better understand capacity retention, and polaron formation. 
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