<p>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&#xa0;MPa for particle rounding and &gt; 14.86&#xa0;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&#xa0;°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.</p> Graphical abstract <p></p>

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Fast-charging natural graphite anodes: synergistic effects of optimized spheronization and TLE-tailored pitch coating

  • Seung-Jae Ha,
  • Hyocheol Lee,
  • Changkyu Kim,
  • Min-Seong Jo,
  • Taehyeon Kim,
  • Jin-Yong Hong,
  • Young-Pyo Jeon

摘要

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.

Graphical abstract