Interfaces and interphases are at the heart of the electrochemical reactions. Manipulating interfaces and interphases so that the electrochemical reactions and processes take place in a controlled and desired way can have a profound impact on the performance of the electrochemical energy storage and conversion devices. In the past years, there have been significant efforts in understanding interfaces and interphases in electrochemical energy devices such as batteries, fuel cells, and electrolyzers. These advances include metal ion (Li+, Na+, Mg2+, etc.) accommodations and charge transfers in batteries, and the oxygen reduction/evolution, the hydrogen oxidation/evolution, and the CO2 reduction, small molecule oxidation, biomass-derived chemicals/fuels upgrading. Yet, despite these efforts, the performance, efficiency, lifetime, and cost still need further improvements; materials innovation and discovery, fundamental insights of these interfaces/interphases will play a critical role in aiding these developments; In-Situ/Operando methods e.g. TEM and spectroscopy and related simulation tools are emerging, even well established for some cases, as a critically important approach for directly probing electrochemical interfaces/interphases, providing essential insight to mechanism understanding, new solutions and materials discovery. The aim of this symposium is to provide an interdisciplinary discussion forum about the current status and future perspectives, including challenges and opportunities in this field.