In the past, the understanding of electrochemical reactions majorly relied on the monitoring and recording of the change of current and voltage, as well as the interpretation of the relations between them. In recent decades, a variety of spectroscopy methods have been used as complementary means to explore electrochemical reactions such as battery reactions, electrocatalysis reactions and electrolysis, etc. However, in most reported cases such characterizations were ex situ or postmortem. In situ or operando observations are in general more difficult as they require tremendous design and instrumentation efforts incorporating the electrochemical devices into the analytical testing platforms.

Since started in 2014, our group at the Woodruff School of Mechanical Engineering at Georgia Tech has been working on developing state-of-the-art X-ray based in situ tools for a variety of electrochemical reactions and devices. Lab X-ray diffractometer based setups were built to perform operando XRD examination on Li-ion and Na-ion batteries in charge-discharge cycling. Our recent research on design of high capacity cathode materials for sodium ion batteries will be reported and the phase transitions during the electrochemical intercalation/deintercalation of Na-ions were cleared observed and interpreted by the in-house operando XRD setup. Another example research based on synchrotron X-ray took the advantages of the high energy, high flux and high Q- and time-resolutions of the synchrotron facilities. In addition, research of in situ XRD for synthesis will also be presented, as the controlling and tuning of the materials is very important for materials used in electrochemical reactions.