Lifetime Prediction of Lithium Ion Batteries by Using the Heterogeneity of Graphite Anodes

Lithium ion batteries for electric vehicles demand high-levelmonitoringof their safety and long-term cyclability. To this end, identifyingdefective cells at the postmanufacturing stage would be the most effectiveapproach. Here, we introduce the lithiation heterogeneity as a keydescriptor for inspecting and grading as-manufactured cylindricalcells. Specifically, the peak intensity of the differential voltage(DV) profile during charge provides a quantitative indication of theheterogeneity of lithium ion intercalation into graphite, in relationto the staging effect of the graphite anode. The degree of heterogeneitydetermined by the DV profile is closely correlated with the cyclelife, implying that the heterogeneity analysis can serve as a usefultool for inspecting as-manufactured cells and predicting their cyclelife at an early stage. Moreover, the ability to accurately gradeas-manufactured cells allows a high-performance battery module tobe built by integrating cells with low heterogeneity and minor deviationsin their performance.