Electrochemistry coupled with mechanics dictates the microstructural evolution and service life of many materials in the energy industry, and underlies problems such as stress-corrosion cracking and battery cyclability.
While atomistic and first-principles modeling is adept at looking at the finer details of energetics and microstructural evolution, it often needs help from experiments to identity the key performance-limiting processes. Here we report the creation of a nanoscale electrochemical testing platform inside a transmission electron microscope (TEM), consisting of electron-transparent single nanowire electrodes and an ionic liquid electrolyte, and direct observations of the electrochemical lithiation and delithiation of the nanowires.
SnO2, ZnO, Si, Ge, graphene and carbon nanotube anodes and LiFePO4 nanowire cathode have been tested so far. Lithium embrittlement is found to be a persistent phenomenon in these materials. These in situ experiments greatly complement our modeling efforts, and together they provide unprecedented details and deep insight into how materials degrade in service due to combined electrochemical-mechanical actions.