The advantages of thick electrodes in improving energy density at the cell level has been reported in many lithium-ion battery papers. Thick electrodes increase energy density by reducing the fraction of the cell dedicated to inactive components, in particular current collectors and separators. However, thick electrodes increase electron and ion transport path lengths through the electrode which increases cell resistance and can result in limited current densities of battery operation.

In this presentation the fabrication and characterization of cells with thick electrodes will be described. These electrodes are produced via hydraulic pressing and mild thermal treatment of active material powders as opposed to conventional casting of composite slurries. These electrodes thus have no binders or conductive additives, which would be expected to increase the diffusion of ions through the electrolyte-impregnated void regions within the electrode. However, these all active material electrodes can now have multiple processes that might limit their rate of charge/discharge, including transport of ions through the electrode microstructure, transport of ions through the solid active material particles, and transport of electrons through the all active material electrode matrix to the current collector. To provide insights into the processes that are limiting the current density in the high energy electrodes, we will describe the use of neutron imaging. Neutron imaging is highly sensitive to the lithium concentration within the battery cell, and thus regions undergoing lithiation/delithiation can be interrogated in operando during charge/discharge of the cell. The lithiation/delithiation profiles provide insights into what process limits the cell and opportunities to improve the performance of these thick electrodes fabricated with less common processing routes.