Electrochemical Strain Microscopy with Blocking Electrodes: The Role of Electromigration and Diffusion

TL;DR

This paper analyzes electrochemical strain microscopy (ESM) with blocking electrodes, focusing on how electromigration and diffusion influence image formation, response frequency, resolution, and detection limits in solid state ionic devices.

Contribution

It provides a detailed analysis of the ESM image formation mechanism considering electromigration and diffusion effects with blocking electrodes, advancing understanding of local ionic flow detection.

Findings

Frequency dependence of ESM response characterized.

Diffusion and electromigration effects quantified.

Resolution and detection limits analyzed.

Abstract

Electrochemical strains are a ubiquitous feature of solid state ionic devices ranging from ion batteries and fuel cells to electroresistive and memristive memories. Recently, we proposed a scanning probe microscopy (SPM) based approach, referred as electrochemical strain microscopy (ESM), for probing local ionic flows and electrochemical reactions in solids based on bias-strain coupling. In ESM, the sharp SPM tip concentrates the electric field in a small (10-50 nm) region of material, inducing interfacial electrochemical processes and ionic flows. The resultant electrochemical strains are determined from dynamic surface displacement and provide information on local electrochemical functionality. Here, we analyze image formation mechanism in ESM for a special case of mixed electronic-ionic conductor with blocking tip electrode, and determine frequency dependence of response, role of diffusion and electromigration effects, and resolution and detection limits.