For the past decades, natural graphite has been widely used as anode material in commercial Li-ion batteries. Although natural graphite holds the strong merits such as low cost and stable performance, there are several issues to consider natural graphite; safety issue due to Li dendrite formation at low charge potential close to that of Li metal, its low gravimetric capacity and volumetric capacity than theoretical values of 372 mAhg⁻¹ and 850 mAhcm⁻³, respectively, and a large initial irreversible capacity loss due to solid electrolyte interphase (SEI) formation.² Those deleteriously affect the safety and performance of Li-ion batteries. Artificial graphite, which is a material made from petroleum or coal tar, provides higher safety, reliability and performance than natural graphite.³ However, the effects of the type of artificial graphite on the SEI formation and their correlation to cycling performance are little reported. Here, we present the systematic investigation of the SEI formation behavior depending on the characteristics of model artificial graphite (AG) anode active materials,⁴ which include different particle characteristics including particle size, surface area and graphitization degree, etc., in the conventional electrolyte with 1 wt% vinylene carbonate (VC) additive as a SEI forming agent, and the correlation among particle characteristics, the SEI formation and stability, interfacial resistances and cycling performance of Li//AG half-cells and full-cells of AG//LiCoO₂.

Acknowledgements

This work was supported by Research Institute of Industrial Science & Technology (RIST).

References

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