Resolving Local Electrochemistry at the Nanoscale via Electrochemical Strain Microscopy: Modeling and Experiments

Abstract: Electrochemistry is the underlying mechanism in a variety of energy conversion and storage systems, and it is well known that the composition, structure, and properties of electrochemical materials near active interfaces often deviates substantially and inhomogeneously from the bulk properties. A universal challenge facing the development of electrochemical systems is our lack of understanding of physical and chemical rates at local length scales, and the recently developed electrochemical strain microscopy (ESM) provides a promising method to probe crucial local information regarding the underlying electrochemical mechanisms. Here we develop a computational model that couples mechanics and electrochemistry relevant for ESM experiments, with the goal to enable quantitative analysis of electrochemical processes underneath a charged scanning probe. We show that the model captures the essence of a number of different ESM experiments, making it possible to de-convolute local ionic concentration and diffusivity via combined ESM mapping, spectroscopy, and relaxation studies. Through the combination of ESM experiments and computations, it is thus possible to obtain deep insight into the local electrochemistry at the nanoscale.