Accelerated Aging Characterization of Lithium-Ion Cells in Automotive Applications - Development of an Appropriate Reference Cycle

An accelerated aging characterization is a prerequisite for the industrial process of battery design and thus for the promotion of electromobility in the market. For this issue, an appropriate reference cycle is essential. The suitability of conventional reference cycles – such as the WLTP Class 3 – for aging characterization is questionable as different aging-relevant load regimes in comparison to real driving cycles are occupied as demonstrated by load spectrum analysis in a former publication. By using a Markov-Chain-Monte-Carlo method, a reference current profile (RCP) is developed that reproduces aging-relevant load conditions in automotive applications. In addition, a temperature-related approximation of this profile (RCPapprox) with a reduced load dynamic is developed that enhances the experimental implementation and reproducibility. Both profile candidates are investigated experimentally with a focus on the resulting effects and mechanisms of aging. The results show, that RCP and RCPapprox actuate a comparable aging on the investigated cell candidate on effect and mechanism level. The results for changing capacity (ΔC) or DC resistance (ΔRDC,10s) allow the assumption that by using RCP or RCPapprox an accelerated aging is initiated that maps the expectable cell aging under realistic automotive loads within a reduced test time.     «

An accelerated aging characterization is a prerequisite for the industrial process of battery design and thus for the promotion of electromobility in the market. For this issue, an appropriate reference cycle is essential. The suitability of conventional reference cycles – such as the WLTP Class 3 – for aging characterization is questionable as different aging-relevant load regimes in comparison to real driving cycles are occupied as demonstrated by load spectrum analysis in a former publication...     »