Designing Hysteresis Free High-Valent Redox Cathode Materials for Electrochemical Application

Advances in electrochemical devices such as batteries, fuel cells, and water-splitting<br/>membranes are making global transition towards clean and renewable energy more possible than<br/>ever. Foundational to (electro)chemical and catalytic transformations in these devices are a stable<br/>and reversible high-valent redox couples. In particular, the phenomenon of high-valent oxygen<br/>redox (anionic redox) in lithium- and sodium-ion positive electrodes has the potential to<br/>significantly improve cell energy density by providing additional high voltage capacity beyond<br/>that of most transition metal redox couples. However, the additional capacity from (anionic redox)<br/>has come at the expense of reduced reversibility in the form of voltage hysteresis and voltage fade.<br/>As a result, high valent redox couples have been historically avoided. In this talk, first, I will<br/>outline the mechanism and the framework for understanding the source of poor electrochemical<br/>reversibility in high valent redox. Second, I will demonstrate a mechanism where structural<br/>disorder and voltage hysteresis can be completely avoided. I will finish my talk by discussing a set<br/>of actionable design rules to engineer materials for different applications that involve high valent<br/>redox couple.