Determination of the SOH estimation indicator and the temperature influence on the Lithium-ion battery in the EV/PHEV applications

For reliable and safe operation of Lithium-ion batteries using in electric or hybrid vehicles, diagnosis of the battery aging states is necessary. But one of the biggest challenges is which indicator can be used to show the battery state-of-health (SOH), otherwise, temperature is the most important external impact factor influencing the value of the indicator, and, furthermore, the performance of Lithium-ion battery used in electric vehicle. In this paper, the application-driven research method is adopted to reveal the fading law of Lithium-ion battery, and the degradation characteristics under the Electric Vehicle (EV) mode and the Plug-in electric vehicle (PHEV) mode are all discussed based on the analysis of the accelerated testing results. And the indicator related to the measurement of the battery SOH is discussed, then we go further to discussed the affection mode and internal mechanism of temperature on the indicator of capacity and internal resistance, which is analyzed qualitatively based on the accelerated life testing results. As the clean energy vehicles become more and more popular in the world, studies in this field will be a hot spot and significant in the future.