Commercial lithium-ion battery electrodes are composed of composites that contain active material, conductive additive, and polymer binder. To increase the energy density at the cell level, both thicker electrodes and the reduction or elimination of the inactive material (conductive additive and binder) is desired. One route to achieve both these routes is to fabricate thick electrodes comprised of only active material, where the active material is moderately sintered for mechanical stability. Such electrodes are less common in the literature, and are rarely paired as full cells. While sintered electrodes have very high energy density, there is a tradeoff of lower electronic conductivity within the electrode and longer lithium ion diffusion pathways. Understanding the limitations and designs of these electrodes is the focus of this presentation. In this study, Li4Ti5O12 (LTO)/LiCoO2 (LCO) full cell with sintered electrodes were produced via sequential synthesis, processing, and fabrication steps. To obtain insights into the discharge processes in these cells and the net movement of lithium, neutron imaging was performed in situ during electrochemical processes. The neutron imaging resulted in clear observation of the net movement of lithium in the cells. The neutron images were used to gain insights into the behavior of the sintered LTO/LCO cells with different electrode thicknesses and different rates of discharge. The results for the movement of lithium within the electrodes was 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.

Characterization of lithiation/delithiation of thick sintered lithium-ion battery electrodes using neutron imaging

2019 Spring National Meeting

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