Probing Transport Limitations in Thick Sintered Battery Electrodes with Neutron Imaging
Daniel S. Hussey, Gary Koenig, Jacob LaManna, David L. Jacobson
Lithium-ion batteries receive significant research effort due to their advantages in energy and power density that is important to enabling many devices. One route to further increase energy density is to fabricate thicker electrodes in the battery cell, however, careful consideration must be taken when designing electrodes as to how increasing thickness impacts the multiscale and multiphase molecular transport processes, which can limit the overall battery operating power. Design of these electrodes necessitates probing the molecular processes when the battery cell undergoes electrochemical charge/discharge. One tool to provide in situ insights of the cell is neutron imaging, because neutron imaging provides information of where electrochemical processes occur within the electrodes. In this manuscript, neutron imaging is applied to track the lithiation/delithiation processes within electrodes at different current densities for a full cell with thick sintered Li4Ti5O12 anode and LiCoO2 cathode. The neutron imaging reveals that the molecular distribution of Li+ during discharge within the electrode is sensitive to the current density, or equivalently discharge rate. An electrochemical model provides additional insights into the limiting processes occurring within the electrodes. In particular, the impact of tortuosity and molecular transport in the liquid phase within the interstitial regions in the electrode are considered, and the influence of tortuosity will be shown to be highly sensitive to the current density. Qualitatively, the experimental results suggest the electrodes behave consistent with the packed hard sphere approximation of Bruggeman tortuosity scaling, which indicates the electrodes are largely mechanically intact but also that a design that incorporates tunable tortuosity could dramatically improve performance of these types of electrodes.
, Koenig, G.
, LaManna, J.
and Duewer, D.
Probing Transport Limitations in Thick Sintered Battery Electrodes with Neutron Imaging, The Royal Society of Chemistry, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928597
(Accessed June 26, 2022)