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9 7 I H I G H L I G H T S 2 0 2 3

PRINCIPAL PUBLICATION AND AUTHORS

From waste graphite fines to revalorized anode material for Li-ion batteries, J.C. Abrego-Martinez (a), Y. Wang (a), V. Vanpeene (b), L. Roué (a), Carbon 209, 118004 (2023); https:/doi.org/10.1016/j.carbon.2023.118004 (a) Institut National de la Recherche Scientifique (INRS) - Centre Energie, Matériaux, Télécommunications (EMT), Varennes, QC, (Canada) (b) ESRF

REFERENCES

[1] P. Cloetens et al., Appl. Phys. Lett. 75(19), 2912-2914 (1999). [2] G. Martínez-Criado et al., J. Synchrotron Radiat. 23(1), 344- 352 (2016). [3] B. Biber et al., Carbon 201, 847-855 (2023).

non-coated material by nearly a factor of two. At the particle level, the total volume of inner decomposition layer formed in the graphite aggregates was reduced by nearly a third on the pitch-coated particles (Figure 75d and e).

The striking difference between the two formulations highlights the benefits of the coating step for reducing the continuous SEI formation both on the surface of the active material and inside the aggregates. The image analysis directly supports the important difference measured in terms of cumulated irreversible capacity, defined as the sum over cycles of the excess lithiation capacity versus delithiation capacity at each cycle, which is mainly related to the SEI formation (Figure 75a). After 200 cycles, the coated active material displayed half the cumulative irreversible capacity compared to the bare aggregated graphite particles, which results in electrochemical

performances comparable to commonly used industrial battery-grade graphite.

This work highlights the clear advantages of X-ray nanotomography for precise assessment of the complex microstructure of battery electrodes down to the nanoscale. It demonstrates the impact of the application of electrode calendering for increasing energy density, and also establishes the benefits of petroleum pitch coating for increasing electrode cycle life and performance. Furthermore, it correlates irreversible lithium loss with the growth of the SEI layer in cycled electrodes, thus identifying a coating method to mitigate this loss. Overall, it shows the benefits of an innovative strategy for successful recycling and re-integration of waste graphite into the production chain of anodes for lithium- ion battery manufacturers, which could lead to increased productivity.

Fig. 75: Evolution during cycling of (a) cumulative irreversible capacity and electrode/particle microstructures for (b,d) uncoated and (c,e) coated graphite agglomerates after 200 cycles.