Delineating local electromigration for nanoscale probing of lithium ion intercalation and extraction by electrochemical strain microscopy

Abstract

Lithium (Li) ion intercalation and extraction are critically important for high performance Li-ion batteries, and they are highly sensitive to local crystalline morphologies and defects that remain poorly understood. Using electrochemical strain microscopy (ESM) in combination with local transport analysis, we demonstrate that we cannot only probe Li-ion concentration and diffusivity with nanometer resolution but also map local energy dissipation associated with electromigration of Li-ions. Using these techniques, we uncover drastic differences in ESM response and energy dissipation between micro- and nano-crystalline lithium iron phosphate (LiFePO4) under different charging states, which explains the superior capacity observed in Li-ion batteries with nanocrystalline LiFePO4 electrode.