Fabrication and Characterization of Thick Sintered Lithium-Ion Battery Full Cells

Abstract

Commercial battery electrodes are composites containing electroactive material and inactive material – typically carbon conductive additives and polymer binders. Eliminating the inactive components would increase the energy density at the cell level. In addition, processing the electrodes to be thicker would improve energy density. One way to achieve both these goals is to fabricate thick electrodes comprised of only sintered active material. Such electrodes have not been extensively investigated, in particular in full cell configurations. Sintered electrodes have very high energy density, but they have relatively low electronic conductivity and longer ion diffusion pathways. Understanding the limitations and designs of these electrodes is the focus of this presentation. Li4Ti5O12 (LTO)/LiCoO2 (LCO) full cells with sintered electrodes were produced via custom synthesis, processing, and fabrication steps. The net movement of lithium was tracked using neutron imaging during electrochemical charge and/or discharge. The neutron imaging resulted in clear observation of the net movement of lithium in the cells. The neutron images provided insights into the lithiation and delithiation processes with different electrode thicknesses and different rates of discharge. The neutron imaging results were compared to electrochemical models of the discharge of the cell. The changes in concentration calculated using the model had good overall agreement with the neutron imaging observations, although improvements to the technique and model inputs will be discussed.