Detecting “Real” End-of-Life of Spent EV Lithium-Ion Battery for Second-Life Applications

The rapid growth of Li-ion battery electric vehicles (EVs) is a major boon for the transportation sector for mitigating or completely removing greenhouse gas emissions from our roads. However, growing numbers of spent EV-batteries present a serious threat to our environment and waste-management challenge for recyclers. As Li-ion batteries in electric vehicles reach the end-of-life (EOL) when their capacity reaches 80% of the nominal value, there is plenty of capacity left in them, which can be used in less-power demanding second-life applications. Thus, it is possible to reduce some burden from our environment and recyclers by promoting the second use of spent EV-batteries and extending battery life in the second-life applications. In the present work, we have demonstrated a novel, synergistic electro-thermal characterization methodology for gateway analysis of spent EV-batteries to determine suitability for second-life applications. We have detected electrode degradation and the “real” EOL by incremental capacity analysis and infrared thermography. Uniquely, and for the first time, this study highlights the impact of non-uniform heat generation due to non-uniform current distribution near the battery’s “real” EOL. Moreover, present results provide a greater understanding of the degradation processes and as such inform industrial battery design to aid prolonged EV battery life in both primary and secondary applications. Most importantly, this study represents an important first step for “real” end-of-life detection that can be applied on large-size pouch cells with different chemistries and this is an area ripe for further exploration.