Characteristic Analysis of Internal Resistance on Lithium-ion Battery for Parameter Selection in Safety Diagnosis

Internal resistances (IR) of lithium-ion battery as one of critical parameters for safety diagnosis of energy storage system (ESS) were analyzed based on a time ratio for characterizing the performance of batteries by using the direct current – internal resistance (DC-IR) method after solving electro-chemical governing equations with the finite element analysis (FEA). Recently, the IR has been interested to check the status of lithium-ion battery related to a safety issue, but the specific definition is relatively ambiguous for ESS. To test the characteristics of IR, here we adopted a numerical approach and tried to show the variety of IR due to a time ratio. Until now, the numerical analysis technique has been developed for analyzing the lithium-ion battery and we have also implemented the DC-IR process incorporating with FEA. By using this numerical setup, the various values of IR were calculated with the different time ratios of voltage and interpreted based on the electro-chemical process. The values of IR were different from the time ratio and IR should be properly defined as its application areas. Additionally, a brief diagnostic process was also proposed for safety considering an online-monitoring system. It is believed that IR will be more strictly defined once defect data becomes available.