Seeing Electrochemistry at the Atomic Scale

A new generation of detectors and nanofabricated electrochemical cells for electron microscopy and spectroscopy have made it practical to characterize electrochemical systems with high spatial resolution. The ability to resolve and isolate the different types of local atomic structures at potential catalytic sites and quantify their distributions is especially valuable given the inhomogeneous nature of many electrochemical systems. Today we have the ability to resolve individual atoms and determine composition and bonding at atomic resolution, but in many electrochemically active systems, resolution is dose-limited by radiation damage. To make the most efficient use of the fewest number of imaging electrons we have developed new high-speed, high-dynamic-range detectors and ptychographic phase-retrieval algorithms to collect the complete scattering distribution and unscramble multiple scattering. These approaches have allowed us to image the 3D structure of battery electrodes and fuel cell cathodes at the atomic scale, visualizing surface and subsurface strains, and detect not only light elements such as hydrogen and lithium, but also their displacements, ordering and vacancies.