Modification of Degradation Mechanism Identification Technique for Cell Grading

The service life of the retired automotive lithium-ion battery (LIB) can be extended through reusing without major changes and reusing through remanufacturing. Reusing through remanufacturing at the module level likely outweigh remanufacturing at the cell level and reusing without major changes. To remanufacture a battery pack, cells/modules are required to be graded and cells/modules in a remanufactured pack needs to be at identical state. The current approach utilises cell/module capacity i.e. State of Health (SoH), to grade the cells/modules at the end of first life. However, the only capacity may not be enough to match the cells/modules; how the cells/modules have been degraded (degradation mechanism, DM) may play a vital role in defining their performance in second life. However, the existing DM detection techniques are not designed to grade the cells/modules at the end of the first life. In this paper, a modified DM detection process is proposed. Here, the proposed modified DM detection process is verified by applying them to the degradation experimental results. Employing the proposed modified DM detection method, cells at same SoH at the end of first life can be graded based on their DM.