3D Simulation of Microstructure Effects in Alkaline Battery Cathodes
The 3D simulation is based on the Monte Carlo method, in which a model generates a series of configurations that satisfy physical constraints in a statistically average way. The microstructure model is solved on a grid and is therefore called the stochastic grid (SG) model. The SG model is built by using the key statistics from microstructure analysis of FIB/SEM image of cathodes and includes short- and long-range order parameters. Toward this end, the work includes a full 3D reconstruction of a cathode using a sequence of 2D FIB/SEM images. This enables us to validate the SG model using measured microstructures. The SG model is additionally validated by electronic and ionic transport measurements.
Figure 1 shows preliminary 3D simulation results of particle distributions within the cathode. The model can describe the connectivity and distribution of carbon and porous domains throughout the cathode, which corresponds to the electron and ion pathways of interest. The model results suggest that carbon additives function more to make short-range connections, rather than long-range highways for electrons. The effective electronic conductivity calculated from the SG model is highly dependent on EMD intrinsic conductivity and contact resistances between particles, which suggests some possible electrode performance improvements may be possible through modified EMD particle arrangement.
The following will be presented and discussed: (1) a validated 3D model that effectively predicts microstructure and conductivity, which can be extended to multiple alkaline battery candidate systems; (2) Qualitative and quantitative model predictions of the performance effects of different carbon additives, pore volume fractions, and EMD distributions.
 Y Wen, Dean Wheeler. 3D Model and Experiments for Understanding Carbon Additive Behavior in Primary Alkaline Cells, ECS meeting, Canada, 2012, abstract number: 420
 Doug R. Never, Dean Wheeler. Effect of Carbon Additives On the Microstructure and Conductivity of Primary Alkaline Battery Cathodes, ECS meeting, San Francisco, 2012, Abstract Number: 285
Figure 1: Preliminary 3D simulation results of particle distributions within a primary alkaline battery cathode. White represents large-size pores, gray represents EMD active material, and black represents graphite additive.