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

Lithium ion batteries for electric vehicles demand high-level monitoring of their safety and long-term cyclability. To this end, identifying defective cells at the postmanufacturing stage would be the most effective approach. Here, we introduce the lithiation heterogeneity as a key descriptor for inspecting and grading as-manufactured cylindrical cells. Specifically, the peak intensity of the differential voltage (DV) profile during charge provides a quantitative indication of the heterogeneity of lithium ion intercalation into graphite, in relation to the staging effect of the graphite anode. The degree of heterogeneity determined by the DV profile is closely correlated with the cycle life, implying that the heterogeneity analysis can serve as a useful tool for inspecting as-manufactured cells and predicting their cycle life at an early stage. Moreover, the ability to accurately grade as-manufactured cells allows a high-performance battery module to be built by integrating cells with low heterogeneity and minor deviations in their performance.