Probing transport limitations in thick sintered battery electrodes with neutron imaging

Abstract

Neutron images indicating redistribution of lithium during discharge at different rates for a battery containing thick sintered electrodes.

Thick Sintered Electrode Lithium-Ion Battery Discharge Simulations: Incorporating Lithiation-Dependent Electronic Conductivity and Lithiation Gradient Due to Charge Cycle

“…The model previously employed largely captured the qualitative polarization and Li + redistribution characteristics during discharge that were observed experimentally, 5 , 7 however, there were significant quantitative differences in the polarization curves. These differences were in part speculated to be due to the assumption of a single electronic conductivity for the electrode matrix in the sintered electrodes.…”

“…The lack of binder and high surface area conductive additives can improve Li + transport properties through the electrode microstructure, however, at such large thicknesses mass transport limitations will still limit the rate capability and current densities batteries containing thick sintered electrodes can achieve. 5 , 7 Recent in operando neutron imaging experiments with thick sintered electrodes provided evidence further supporting Li + transport in the electrolyte phase through the electrode microstructure limiting the rate capability of batteries containing these electrodes, 7 and experimental results were compared to simulations using the 1-D model based on Newman et al 8 …”

“… 8 , 9 However, for sintered electrodes there were no conductive additives, and thus the electronic conduction must proceed through the active material itself, including interparticle connections. For the system considered in this manuscript and previously reported, 7 the anode material was Li 4 Ti 5 O 12 (LTO) and the cathode material was LiCoO 2 (LCO). For both LTO and LCO, the electronic conductivity is dependent on the extent of lithiation of the active material.…”

Recent Progress on Advanced Imaging Techniques for Lithium‐Ion Batteries

“…The nonuniform distribution indicates that there is a limit on lithium diffusion in the electrode at a relatively high cycle rate during the lithiation process. Besides, Nei et al [ 88 ] applied neutron imaging to probe the lithiation/delithiation processes at different current densities in Li 4 Ti 5 O 12 /LiCoO 2 full cell. Neutron imaging proved that the discharge capacity is limited as the intercalation of lithium only occurs near the separator.…”

“…The nonuniform distribution phenomenon can be also visualized by other imaging methods such as EELS–TEM, Raman–SEM, optical imaging, X‐ray imaging, and neutron imaging. [ 42,72,88,104 ] EELS–TEM and Raman–SEM can only reveal the uneven lithiation happened in single‐particle or between several particles at the microscale, and specially designed cells are required for in situ measurements. Optical imaging can produce the SOC image on a larger scale by monitoring the color change of the graphite during its lithiation process.…”