Lithium-ion batteries (LIBs) are widely used as key components in electric vehicles (EVs) and energy storage systems (ESS) owing to their high energy density, long cycle life, and stable operation. The rapid expansion of the EV market has intensified the demand for advanced graphite anode materials that combine cost competitiveness with superior electrochemical performance, including fast-charging capability and structural stability. This study presents an integrated approach for optimizing the physical spheronization of natural graphite and synthesizing a high-performance coating pitch (CP) for chemical spheronization. The correlation between mechanical stress and morphological evolution during the process was quantitatively analyzed using an Air Classifier Mill (ACM). Optimal spheronization was achieved by aligning theoretically calculated stress levels (≈ 3.72 MPa for particle rounding and > 14.86 MPa for fracture) with experimental results. High-performance coating pitches were prepared via stepwise polymerization of pyrolysis fuel oil (PFO), followed by Thin Layer Evaporation (TLE)-based molecular weight distribution tailoring. The resulting pitch exhibited a softening point of 279.4 °C, coking value of 70.7%, and zero quinoline insoluble (QI) content, and was applied as a coating precursor. The optimized spheronized graphite anode showed excellent electrochemical properties, including an initial Coulombic efficiency of 92.6% and 97.4% capacity retention after 50 cycles. Electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) analyses further confirmed efficient lithium-ion diffusion at both the surface and core, demonstrating suitability for fast-charging LIB applications.

Fast-charging natural graphite anodes: synergistic effects of optimized spheronization and TLE-tailored pitch coating
    Abstract
    1 Introduction
    2 Experimental
        2.1 Physical spheronization of natural graphite
        2.2 Coating pitch synthesis
        2.3 Dry coating process
        2.4 Electrochemical characterization
        2.5 Characterization
    3 Results and discussion
        3.1 Characterization of spheronized natural graphite
        3.2 Characterization of coating pitch
        3.3 Characterization of the coated spherical natural graphite
        3.4 Electrochemical characterization of the coated spherical natural graphite
    4 Conclusion
    References

• Seung-Jae Ha(Hydrogen Process Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea)
• Hyocheol Lee(Hydrogen Process Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea)
• Min-Seong Jo(Hydrogen Process Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea)
• Changkyu Kim(Hydrogen Process Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea, Advanced Materials and Chemical Engineering, University of Science and Technology (UST), Daejeon, Republic of Korea)
• Taehyeon Kim(Hydrogen Process Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea, Advanced Materials and Chemical Engineering, University of Science and Technology (UST), Daejeon, Republic of Korea)
• Jin-Yong Hong(Hydrogen Process Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea, Advanced Materials and Chemical Engineering, University of Science and Technology (UST), Daejeon, Republic of Korea)
• Young-Pyo Jeon(Hydrogen Process Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea, Advanced Materials and Chemical Engineering, University of Science and Technology (UST), Daejeon, Republic of Korea) Corresponding author