2, The University of Utah, Salt Lake City, Utah, United States
An understanding of Lithium (Li) spatial distribution within the electrodes of a Li-ion cell, during charge and discharge cycles, is essential to optimize the electrode parameters for increased performance under cycling. Neutron tomography, which enables mapping of the three-dimensional distribution of elements causing significant neutron attenuation, has been applied to investigate the spatial distribution of Li within Vanadium Pentoxide (V2O5) electrodes of a small coin cell. The neutron attenuation data has been used to construct the three-dimensional Li spatial images. The attenuation data from bulk sections and three planes parallel to the plane of the electrode have been averaged to quantify the Li distribution at various states of charge/discharge. It is shown that there is sufficient neutron imaging contrast between lithiated and delithiated regions of V2O5 electrode making it possible to map Li distributions even in small electrodes with thicknesses < 1 mm. The images reveal that the Li spatial distribution is inhomogeneous and a relatively higher C-rate leads to more non-uniform Li distribution after Li insertion. The non-uniform distribution suggests the limitation of Li diffusion within the electrode during the lithiation process under the relatively high cycling rates.