In situ scanning electron microscopy on lithium-ion battery electrodes using an ionic liquid

► A method for investigating electrodes of lithium-ion batteries inside a scanning electron microscope is introduced. ► Using this method, electrode materials can be investigated during electrode operation with high spatial resolution. ► Morphological in situ observations on SnO2 show the formation of interface layers, large volume expansions, growth of extrusions as well as mechanical damage in the electrodes. ► The electrochemical behavior of SnO2 was found to be particle size dependent.