Rotating Ring Disk Electrode for Monitoring the Oxygen Release at High Potentials in Li-Rich Layered Oxides

Abstract

Li-rich layered oxides show a staggering capacity that relies on cumulative cationic and anionic redox processes. However, their practical applications are plagued by roadblocks dealing with large hysteresis, capacity fade and irreversible oxygen loss during the first charge that causes undesirable structural changes. Hence, the first step to screen the Li-rich layered oxides is the identification of this gas release phenomenon and its better understanding. Online electrochemical mass spectrometry (OEMS) is presently used for the elucidation of gas evolution, but its usage is lengthy and far to be routine. Herein we propose the utilization of the simple rotating ring disc electrode (RRDE) technique for the identification of O2 release phenomenon and hence the quick screening of Li-rich layered oxides. We have evaluated the feasibility of RRDE to monitor the O2 generation by conducting studies on Li-half cells having various Li-rich layered oxides as cathodes and found that our results nicely compare with those obtained by OEMS, hence demonstrating the validity of RRDE technique. The proposed RRDE approach which offers high sensitivity for the identification of O2 release while being fast and simple should greatly help to advance the understanding of oxygen redox processes and promote the design of new materials.