Direct Mapping of Ion Diffusion Times on LiCoO2 Surfaces with Nanometer Resolution

Spatial variability of ionic transport on the polycrystalline LiCoO 2 surface is studied on the ∼10 nanometer level by time-resolved electrochemical strain spectroscopy (ESM). Strong variability between ESM signal relaxation and hence ionic transport at the grain boundaries and within the grains is observed. The relationship between relaxation and ESM hysteresis loop formation is established. The use of these strain measurements allows ionic transport be probed on the nanoscale, and suggests enormous potential for probing ionic materials and devices including batteries and fuel cells.