Development of a Model for Reversible Degradation of Lithium-Ion Batteries

Abstract

To develop technologies aimed at suppressing reversible degradation caused by repeated high-current charge and discharge cycles, we systematically conducted experimental investigations on the changes in battery characteristics (such as resistance and cell surface pressure) in relation to different anode materials and their degradation control factors. The results suggest that the primary mechanism of reversible degradation is the temporary inhomogeneity of reactions within the cell due to the flow of the electrolyte. The driving forces behind this are the expansion and contraction of the anode (graphite) and the osmotic pressure caused by the concentration gradient of Li ions in the electrolyte. Based on this mechanism, we constructed a "tank model" that simulates the one-dimensional flow of electrolyte within the cell to represent reversible degradation. Furthermore, we confirmed that the differences between the experimental results and this model are within a 10% range of agreement.