SOC Detection of Multi-Regional Lithium-Ion Battery Based on Ultrasonic Flexible Sensing Technology

The mechanical properties of the electrodes are dynamic change during the cycle, which will affect the wave propagation characteristics in the lithium-ion battery. It is feasible for the non-destructive characterization of lithium-ion batteries based on the relationship between the wave characteristic and the state of charge (SOC). In this research, an ultrasonic bulk wave detection technique for detecting the SOC of multi-area lithium-ion batteries using arrayed flexible sensors is proposed. Firstly, the simulation model of type 1–3 piezoelectric composites was established based on the finite element simulation software COMSOL, and the effects of different structural parameters, such as piezoelectric phase volume fraction, composite thickness, and piezoelectric column aspect ratio, on their properties were analyzed. Based on the simulation optimization results, a 5×5 1–3 piezoelectric composite sensor was designed and prepared. The ultrasonic bulk wave detection system for lithium-ion batteries was built with the optimized arrayed sensor, and the connection between SOC and wave propagation properties was experimentally investigated, and the inhomogeneity of the SOC of lithium-ion batteries was visualized and analyzed. Furthermore, the ultrasonic flexible sensing detection approach has also been shown to be a sensitive means of determining the SOC of multi-area lithium-ion batteries.