In-Service EV Battery Life Extension Through Feasible Remanufacturing

While a number of publications have addressed the high-level requirements of remanufacturing to ensure its commercial and environmental sustainability, considerably less attention has been given to the technical data and associated test strategies needed for any evidence-based decision as to whether a vehicle energy storage system should be remanufactured - extending its in-vehicle life, redeployed for second-life (such as domestic or grid storage) or decommissioned for recycling. The aim of this paper is to critically review the strategic requirements for data at the different stages of the battery value-chain that is pertinent to an Electric Vehicle (EV) battery remanufacturing strategy.

Discussed within the paper is the derivation of a feasible remanufacturing test strategy for the vehicle battery system. Experimental results are presented that explore the trade-off between test accuracy as a function of key variables such as the ambient temperature at which the measurements are taken, the rate at which electrical current is used to charge/discharge the battery and the relaxation time allowed for the battery to equilibrate before the test is commenced. It is highlighted that the cost and environmental impact of remanufacturing EV battery systems relies heavily on the availability of a viable test strategy. Initial findings from the research are presented and testing on a 20 Ah pouch cell highlights that the variation in discharge capacity due to different temperatures can result in circa: 14% under-estimation. Also, waiting times between test periods (as defined within the best practice standards) can be reduced for different cells to improve testing time efficiency.