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Micro-expanded graphite (MEG), with its expanded interlayer spacing, enhances lithium-ion (Li+) diffusivity and transport efficiency. However, MEG’s high specific surface area of MEG leads to structural instability, which limits its performance in high-rate lithium-ion batteries (LIBs). To address this, MEG was coated with pitch, a conventional carbon precursor, but its lack of surface oxidation functional groups restricts the rate capability enhancement. Herein, maleic acid (MA), which is rich in hydroxyl (–OH) and carboxyl (–COOH) groups, and pitch were used to fabricate MAC@MEG and PC@MEG via a simple coating process. Physicochemical and electrochemical characterizations confirmed a lower specific surface area and higher content of −OH and −COOH groups compared to those of PC@MEG, resulting in superior electrochemical performance. MAC@MEG displayed a specific capacity of 325.81 mAh g−1 at 1 C, retaining 95.01% after 300 cycles and 82.76% after 500 cycles at 3 C. In contrast, PC@MEG retained only 60.51%. Even at 5 C, MAC@MEG maintained a reversible capacity of 117.65 mAh g−1 after 200 cycles.

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Maleic Acid vs. Pitch as Carbon Coating Sources for Micro-Expanded Graphite: Impacts on Lithium-Ion Battery Rate Performance

  • 会议论文

  • 发表日期：

    2025年

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  • Wenjie Wang,
  • Xuan Zhang,
  • Xianchao Wang,
  • Jinling Yin,
  • Guiling Wang,
  • Qing Wen

摘要

Micro-expanded graphite (MEG), with its expanded interlayer spacing, enhances lithium-ion (Li+) diffusivity and transport efficiency. However, MEG’s high specific surface area of MEG leads to structural instability, which limits its performance in high-rate lithium-ion batteries (LIBs). To address this, MEG was coated with pitch, a conventional carbon precursor, but its lack of surface oxidation functional groups restricts the rate capability enhancement. Herein, maleic acid (MA), which is rich in hydroxyl (–OH) and carboxyl (–COOH) groups, and pitch were used to fabricate MAC@MEG and PC@MEG via a simple coating process. Physicochemical and electrochemical characterizations confirmed a lower specific surface area and higher content of −OH and −COOH groups compared to those of PC@MEG, resulting in superior electrochemical performance. MAC@MEG displayed a specific capacity of 325.81 mAh g−1 at 1 C, retaining 95.01% after 300 cycles and 82.76% after 500 cycles at 3 C. In contrast, PC@MEG retained only 60.51%. Even at 5 C, MAC@MEG maintained a reversible capacity of 117.65 mAh g−1 after 200 cycles.