Design of a High Power Battery Based on an Analysis of Data Captured from a Commercial Hybrid Electric Vehicle Running at Operating-Mode Conditions

The automotive industry requires electric vehicle battery systems to maintain specified performance for an 8 year life cycle. However, it has been shown for Li-ion batteries that the capacity loss after a 1 year operation is approximately 3%, and the power loss is approximately 8%. This is primarily due to battery internal resistance increasing over time caused by growth in SEI film thickness and a reduction in electrode adhesion. In this study, data were collected from a commercial hybrid electric vehicle battery system running at operating-mode conditions over a period of 1 year. In total, approximately 340,000 data samples were recorded. Of these data, about 92 % discharge current was less than 50 A and the peak at 150 A; about 97 % charge current was less than 75 A and the peak at 120 A. Based on an analysis of the collected data, a model simulating operating-mode performance was developed. The model addressed the three parameters- temperature, vibration and current. In order to better meet the requirement of commercial hybrid electric vehicles, a high performance 6 Ah high power battery was designed. The maximum charge and discharge current reached 180 A and 210 A, respectively. Using the developed simulation model, it can be shown that the 1-year discharge power loss of the battery is less than 3%, with negligible capacity degradation. It is therefore concluded that the 6Ah high power battery can meet the 8 year life cycle requirement of the automotive industry