In fundamental studies of energy storage systems, particularly electrochemical energy storage (EES), ex situ experiments often provide limited insights due to sample preparation and transfer. More importantly, electrochemical systems often operate at states far from equilibrium, which requires operando characteriztion. On the other hand, the EES systems’ macroscopic properties such as the energy and power density are often governed the electrode/electrolyte interfaces that by nature are of atomic and nano scales.In this work new findings on surface and interface stability affecting the electrochemical longevity of the high voltage cathode material are investigated using a combination of in situ and ex situ imaging and spectroscopic tools, including: transmission X-ray microscopy, synchrotron X-ray absorption spectroscopy, and double-aberration-corrected scanning transmission electron microscopy. These tools unveil that cation migration and subsequent surface structural changes at the atomic levels are majorly responsible for the degradation. Combining the DFT + U calculations with our experimental observations, a correlation between these interface structural instability and the capacity degradation can be established. I will extend some of the tools capabilities to studying lithium and silicon based anode materials, whose interfaces/interphases are extremely complex and dynamically changing with respect to factors such as electrolytes, current density etc. Novel techniques utilizing cyrogenic microsocpy are necessary to probe and understand the interfaces and interphases in these systems.

Probing and understanding interfaces and interphases in electrochemical energy storage systems

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.