Modeling Volume Change and Battery Performance Due to Intercalation in Porous Electrodes

Abstract

In order to accurately predict the behavior or electrochemical devices, it is necessary to develop sophisticated models that take into consideration transport processes, electrochemical phenomena, mechanical stresses, and structural deformations on the operation of an electrochemical system. Many different models exist that can predict the electrochemical performance of these devices under a variety of operating and design conditions.[1-7] However, many of these models assume constant porosity and do not take into consideration the effects of a variable porosity on the porous electrode during cycling and what effects that may have on performance. In recent years, electrodes have been developed that show a significant volume change during intercalation and deintercalation, which are unable to be accurately predicted using these constant porosity models. Porosity and dimensional changes in an electrode can significantly affect the resistance of the battery during cycling and cause premature failure of the battery due to generated stresses. Previously, we have shown the ability to incorporate dimensional and porosity changes in a porous electrode into a model to predict volume changes in the active material during intercalation through the coupling of porous rock mechanics and porous electrode theory.[6] However, that model incorporated many assumptions in order to obtain an analytical solution, including the assumption of bulk stress, strain, and porosity. Here, we present a model that removes those assumptions and illustrates the coupling of porous electrode theory and rock mechanics in order to predict stress, strain, and porosity gradients across a porous electrode during cycling. 1. M. Jain and J. W. Weidner, J Electrochem Soc, 146, 1370 (1999). 2. M. Jain, G. Nagasubramanian, R. G. Jungst and J. W. Weidner, J Electrochem Soc, 146, 4023 (1999). 3. P. M. Gomadam and J. W. Weidner, J Electrochem Soc, 153, A179 (2006). 4. X. C. Zhang, A. M. Sastry and W. Shyy, J Electrochem Soc, 155, A542 (2008). 5. J. Christensen and J. Newman, J Solid State Electr, 10, 293 (2006). 6. T. R. Garrick, K. Kanneganti, X. Y. Huang and J. W. Weidner, J Electrochem Soc, 161, E3297 (2014). 7. K. Higa and V. Srinivasan, J Electrochem Soc, 162, A1111 (2015).