Current Distribution Simulation of Parallel-Connected Modules Using Degraded Lithium-Ion Battery Cells

Abstract

This study introduces a method for determining current distribution during the charging of modules composed of parallel-connected lithium-ion battery cells exhibiting varying levels of degradation. The proposed method was validated by examining current distribution in two- and three-cell parallel modules containing both new and degraded cells, demonstrating that the calculated charging currents were highly consistent with experimental measurements, with discrepancies between 1.1% and 2.2%. Furthermore, an overdistribution phenomenon was observed, where degraded cells received excessive current toward the end of the charging process. Investigation attributed this phenomenon to a rapid alteration in the internal resistance balance during charging. The proposed methodology is extendable to configurations with more than three cells through recursive calculations, highlighting its applicability in designing large-scale energy storage systems and strategies for repurposing used batteries.