Thick Sintered Electrodes with Porosity Gradients to Facilitate Ion Transport

Abstract

Engineering electrode structure such as increasing thickness increases areal energy density and reduces the relative mass and volume allocated to inactive components. However, electrodes with increased thickness encounter ionic and/or electronic transport limitations at high rates of charge/discharge. This poster will describe an investigation of electrodes with porosity gradients. Sintered electrodes were used due to the ability to fabricate relatively thick electrodes using only solid electroactive materials and mild sintering processing. Larger porosity near the separator facilitated ionic transport because this region has greater ion flux relative to regions near the current collector, particularly at high current densities where overall electrode utilization is more restricted to the separator region for both electrodes. A gradient structure would also be desirable because reduced porosity next to the current collector will increase overall cell energy density at lower rates when ion transport restrictions are less of an issue. We will present the experimental and simulation comparisons between electrodes with gradients in porosity, where for comparison the higher porosity is near the separator or current collector region. Electrodes with equivalent total porosity without a gradient structure were investigated as controls.