In-situ Studies of Ion-exchange Synthesis for Developing New Cathodes
Patrick Looney and Feng Wang Group at BNL
Ion exchange is an important method for preparing new cathode materials with metastable structures that are generally inaccessible via direct chemical reactions, but can be obtained via Li+ exchange of Na+ in iso-structural Na-containing compounds. Looney and Wang Group at Brookhaven National Laboratory have developed a new in-situ reactor for real time probing of ion exchange reactions, enabling quantitative measure of intermediate phases and reaction kinetics. In studies of Li+ exchange of Na+ in NaVPO5F compound, it was found that the reaction proceeds via a complicated phase transformation process, towards Li(Na)VPO5F — a new high-energy cathode. This new in-situ technique may also be applied for studies of other type of synthesis reactions, such as hydrothermal, solvothermal and solid-state. Real-time, quantitative identification of structure and phases during synthesis using time-resolved synchrotron XRD provides a new avenue for rational design and preparation of battery materials of desired phases and properties.
Develop high-energy cathodes via hydrothermal ion exchange (A) schematic illustration of in-situ reactor specialized for studies of synthesis reactions, and (B) time-resolved XRD patterns from ion exchange synthesis of Li(Na)VPO5F.