Electrochemical energy storage is the key enabling component of electric vehicles and solar/wind-based energy technologies. The enhancement of energy stored requires the detailed understanding of charge storage mechanisms and electrochemical and electromechanical phenomena over a variety of length scales from atoms to full cells. Fundamental understanding of structure-function correlation in energy materials and devices on the mesoscopic and atomic levels is prerequisite to knowledge-based development that would greatly boost the progress towards improved or targeted electrochemical performance of energy storage systems. Therefore, local probing of electrochemical and electromechanical behaviors on individual structural elements and heterogeneities, from grains to defects and further to individual atomic and molecular species, are invaluable. One challenge with the probing of local electrochemical reactions is the downscaling of current-based measurement, which many standard electrochemical characterization techniques depend on. This is limited by the electrode size which can be fabricated and electric current measurement limitations which do not allow to evaluate electrochemistry on a single particle level. To overcome the scaling problem, ionic currents can be measured indirectly, for example through the interaction of the ion and the electrode material during electrochemical processes, modifying for example electrode structure and mechanical properties. Electro-chemo-mechanical phenomena are universal features of a broad spectrum of ion-based processes. This can strongly affect the materials functionality or lifetime but can also be used as a basis for high-resolution imaging of associated electrochemical processes. Here, force-based atomic force microscopies (AFM) have provided novel insights into locally probing electrochemical mechanisms on tens of nanometer and even molecular length scales and provide a viable pathway to probe electrochemical processes <i>in situ/operando</i>. I will discuss electrochemical AFM methods based on force-feedback in the context of capacitive energy storage including electric double layer and pseudocapacitance for carbon, graphite, MXenes, and metal oxides, as well as other energy storage related systems, which highlights the broad applicability of AFM in the field of energy storage.

Nanoscale electro-chemo-mechanical coupling in capacitive energy storage

ACS Fall 2021

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