Structural, morphological and compositional characterizations of electrochemical systems during various states of biasing provide essential information to understand the fundamental processes controlling their performance and stability. Transmission electron microscopic characterization aids the highest spatial resolution for such characterization, combining real space imaging with local spectroscopic and crystallographic information. In recent years, it has also been used increasingly to directly follow electrochemical reactions in situ. Distinguishing morphological, structural and compositional variations resulting from electrochemistry and from the electron beam is crucial in the field of in situ electrochemistry. In situ electrochemistry in the TEM involves repeated high dose rates on the samples. In electrochemistry, both in case of a liquid system or a solid-state system, electron dose rates play a crucial role for any system to be characterized by in situ TEM experiments. Already during sample preparation, the sample will be exposed to electron and ion beams, which has to be taken into account.
In liquids, the electron beam acts as reducing agent inducing nucleation, dissolution and growth, depending on the type and concentration of solutes and the solvent leading to morphological, crystallographic or compositional changes. In the case of solids, electron beam induced damage might takes place, leading to a modified electrochemistry, which is critical to distinguish from the actual electrochemistry of the system.
In this presentation, I will illustrate examples of both electron beam induced electrochemistry in liquid (e.g., AgNO3, electrolytes) and solid systems, in addition to the electrochemistry of new battery chemistries based on developmental systems such as solid-state fluoride ion batteries.