Simultaneous Neutron and x-Ray Tomography for Advanced Battery Research

The current demand of high powered portable electronics and electric vehicles has put significant strain on current battery technology. To improve performance of advanced battery technologies, such as lithium-air, it is critical to understand how reactive species transport and distribute throughout the cell at varying states of charge. Neutron and x-ray imaging techniques allow in-situ visualization of reactants within the battery. X-ray attenuation increases with increasing atomic number while neutron attenuation is more random with strong attenuation by lithium. These techniques can provide complementary data by providing critical microstructure information. To provide access to both techniques, NIST is developing a simultaneous neutron and x-ray imaging facility. The new system orients a 90 keV microfocus x-ray source 90° to the neutron beam to allow for simultaneous tomography as shown in Figure 1. This x-ray system will allow for variable energy, brilliance, and magnification while matching the neutron spatial resolution of 15-50 micron. Matching image resolution of the two beams will allow the overlaying of the two tomograms. Simultaneously imaging batteries will allow reaction species, such as lithium, and solid structure to be resolved at identical conditions which can’t be guaranteed for serial imaging (possibly at different facilities). This presentation will describe the new simultaneous imaging system and evaluate its measurement uncertainties while assessing its abilities using an assortment of batteries including alkaline, Ni-Cd, and Li-ion.