A scanning probe microscopy approach was developed for exploring voltage-controlled ion dynamics in ionically conductive solids and decoupling transport and local electrochemical reactivity on the nanometer scale. Electrochemical strain microscopy permitted detection of bias-induced ionic motion through the dynamic (0.1-1MHz) local strain. Spectroscopic modes based upon low-frequency (∼1Hz) voltage sweeps allowed local ion dynamics to be probed locally. The bias dependence of the hysteretic strain response accessed through first-order reversal curve measurements demonstrated that the process was activated at a certain critical voltage and was linear above this voltage everywhere on the surface. This suggested that first-order reversal curve spectroscopic electrochemical strain microscopy data separates local electrochemical reaction and transport processes. The relevant parameters such as critical voltage and effective mobility could be extracted for each location and correlated with the microstructure. The evolution of these behaviours with the charging of the amorphous Si anode in a thin-film Li-ion battery was explored. A broad applicability of this method to other ionically conductive systems was predicted.

Decoupling Electrochemical Reaction and Diffusion Processes in Ionically-Conductive Solids on the Nanometer Scale. N.Balke, S.Jesse, Y.Kim, L.Adamczyk, I.N.Ivanov, N.J.Dudney, S.V.Kalinin: ACS Nano, 2010, 4[12], 7349-57