Possibility of degraded location identification in lithium-ion battery with magnetic sensors

The purpose of this research is to investigate the possibility of detecting defects inside a lithium-ion battery (LIB) by a non-contact method. This method detects defects inside the LIB by measuring the magnetic field formed around the LIB during discharging. During repeating 300 cycles of charging and discharging, the magnetic field around the LIB was measured using magnetic sensors. After that, the electric current deviation in LIB by cycles was analyzed with sparse modeling as inverse problem analysis. To induce localized performance degradation within the LIB, a Peltier element was used to cool the cell partially, thereby creating a controlled defect region for evaluation. As a result, it was observed that the number of regions where the internal current deviation exceeded half of the average current progressively increased with repeated charge and discharge cycles. Additionally, a decrease in current was successfully detected in the region subjected to cooling by the Peltier element.