State of health estimation of lithium-ion battery in wide temperature range via temperature-aging coupling mechanism analysis

Abstract

Incremental Capacity Analysis (ICA) has been widely introduced to research aging mechanism and estimate State of Health (SOH) of lithium-ion battery. However, traditional incremental capacity analysis is generally performed at a standard temperature. Actually, temperature also affects the characteristics of Incremental Capacity (IC) curve, resulting in larger estimation error at different temperature. In this paper, compared with different IC curve solving methods, Savitzky-Golay filtering method with less calculation is firstly introduced to obtain smoother IC curve. Secondly, through the correlation analysis between the characteristics of the IC curve and the aging state of the battery, the highest correlation characteristic point is extracted. Subsequently, by analyzing the coupling influence mechanism of temperature and aging on battery impedance, the mechanism functions among the characteristic point, temperature and aging are constructed. Based on the mechanism functions, a SOH estimation method in wide temperature range is then proposed. Finally, the proposed estimation method is verified at -5 °C ∼55 °C, and the results show the maximum estimation error is 4.03%, which indicates that the proposed estimation method can effectively broaden the temperature range of the original incremental capacity analysis method.