Isotropic Volume Expansion of Particles of Amorphous Metallic Alloys in Composite Negative Electrodes for Li-Ion Batteries

Direct observation of the particles of active material as they react in situ is necessary to build an understanding of the growth characteristics in large-volume-change active materials. A comparison between in situ optical and atomic force microscopy observations shows that particles of amorphous large-volume-change active material expand isotropically upon lithium insertion. Using the isotropic expansion upon lithium insertion characteristic of amorphous alloys, the volume change of other amorphous active materials upon lithium insertion can be measured with an optical microscope by observing only the change in particle area.