• 论文
主办单位:煤炭科学研究总院有限公司、中国煤炭学会学术期刊工作委员会
煤系沥青包覆再生石墨微观构造及电化学性能
  • Title

    Microstructure and electrochemical performance of recycled graphite coated with high coking value coal asphalt

  • 作者

    岳彦龙林雄超张玉坤高红凤张续春王永刚

  • Author

    YUE Yanlong;LIN Xiongchao;ZHANG Yukun;GAO Hongfeng;ZHANG Xuchun;WANG Yonggang

  • 单位

    中国矿业大学(北京)化学与环境工程学院

  • Organization
    School of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing
  • 摘要

    石墨负极材料易在石墨层间与电解液发生共嵌入导致石墨层膨胀、粉化脱落,严重影响石墨负极材料的循环稳定性。利用沥青对石墨负极进行包覆,形成不定型碳层包覆的“核壳”结构,可减少石墨层的膨胀脱落,提高石墨负极材料的电化学性能。以中温煤焦油沥青为原料,通过空气氧化和聚合交联制备得到高结焦值、高软化点的包覆沥青。通过液相包覆方法,考察了对再生石墨负极的包覆性能。采用X射线衍射(XRD)、拉曼光谱(Raman)、氮气吸附、扫描电镜(SEM)和透射电镜(TEM)等方法分析了再生石墨包覆形貌与界面微观结构变化,并对材料电化学性能进行了测试。结果表明,沥青包覆可有效完善再生石墨微观构造。随着沥青包覆量的增加,石墨表面缺陷减少,比表面积和孔容降低;炭化后包覆界面形成不定型碳层,包覆界面无序度随沥青包覆量的增加而升高。不定型碳包覆层的形成显著提高了石墨负极性能,包覆12%沥青的再生石墨比容量达到450 mA·h/g,相比未包覆石墨提升140 mA·h/g;沥青包覆石墨负极首次库伦效率增加11.5%,并且循环稳定性获得改善;在5 A·h下比容量提高至285 mA·h/g,相比未包覆再生石墨提高242.8 mA·h/g,倍率性能突出。

  • Abstract

    Graphite-based anode material is easily destroyed by the embedding and decomposing of electrolyte in the graphite layers, resulting in the reducing of battery cycle efficiency and stability. The graphite anode coated with asphalt to form a “core-shell” structure with amorphous carbon layer can alleviate the expansion and exfoliation of graphite layer, and thus improve the electrochemical performance of the graphite anode material. In this study, the coated asphalt with high coking value and high softening point were prepared by air-blowing oxidation and cross-linking polymerization of medium temperature coal-tar pitch. Moreover, recycled graphite anode was coated by as-prepared asphalt using liquid phase coating method, and the coating properties were systematically investigated. The coating morphology and interfacial microstructure of recycled graphite were analyzed by X-ray diffraction (XRD), Raman spectroscopy (Raman), nitrogen adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the electrochemical performance of the anode materials were tested. The results show that asphalt coating can effectively improve the microstructure of recycled graphite. With the increase of asphalt coating amount, the surface defects of graphite decrease, and the specific surface area and pore volume reduce as well. After carbonization, the amorphous carbon layer is formed at the coating interface, and the disorder degree of the coating interface increases with the rise of asphalt coating amount. The formation of amorphous carbon on the coating interface significantly improves the performance of graphite anode. The specific capacity of recycled graphite coated with 12% asphalt reaches 450 mA·h/g, which is 140 mA·h/g higher than that of uncoated graphite. And, the first coulomb efficiency is increased 11.5%, and the cycle stability is improved apparently. Likewise, the specific capacity under 5A·h is enhanced to be 285 mA·h/g, that is 242.8 mA·h/g higher than the uncoated recycled graphite. The coating process using as-prepared coal tar pitch achieved an outstanding rate capability of graphite anode.

  • 关键词

    包覆沥青“核壳”结构氧化交联液相包覆再生石墨

  • KeyWords

    coating pitch;“core-shell” structure;oxidation cross-linking;liquid phase coating;recycled graphite

  • 基金项目(Foundation)
    国家自然科学基金资助项目(22278420);中央高校优秀青年团队资助项目(2023YQTD03)
  • DOI
  • 引用格式
    岳彦龙,林雄超,张玉坤,等. 煤系沥青包覆再生石墨微观构造及电化学性能[J]. 煤炭学报,2024,49(5):2507−2518.
  • Citation
    YUE Yanlong,LIN Xiongchao,ZHANG Yukun,et al. Microstructure and electrochemical performance of recycled graphite coated with high coking value coal asphalt[J]. Journal of China Coal Society,2024,49(5):2507−2518.
  • 图表

    Table1

    原料沥青与包覆沥青组成及性质
    样品 软化点SP/℃ 结焦值CV/% w(HS)/% w(HI-TS)/% w(TI-QS)/% w(QI)/%
    原料沥青 215.00 60.44 32.00 37.00 28.23 2.77
    包覆沥青 272.70 83.40 3.62 34.69 53.79 7.90

    Table2

    反应温度对沥青的性质与组成影响
    反应温度/℃ 空气流量/(mL·min−1) 反应时间/h CV/% SP/℃ w(HS)/% w(HI-TS)/% w(TI-QS)/% w(QI)/%
    300 90 2 75.76 226.30 13.88 41.62 40.86 3.64
    310 78.98 239.40 12.30 35.67 47.33 4.90
    320 79.18 258.90 9.23 37.33 47.42 6.02
    330 80.83 265.50 6.55 35.27 51.35 6.83
    340 83.40 272.70 3.62 34.69 53.79 7.90

    Table3

    空气流量对沥青性质及组分的影响
    反应温度/℃ 空气流量/(mL·min−1) 反应时间/h CV/% SP/℃ w(HS)/% w(HI-TS)/% w(TI-QS)/% w(QI)/%
    340 50 2 79.07 222.20 25.77 41.21 27.37 5.65
    60 80.22 227.30 21.99 44.50 28.83 4.68
    70 80.40 232.40 21.70 39.97 32.17 6.16
    80 82.48 264.70 16.48 42.44 33.84 7.24
    90 83.40 272.70 3.62 34.69 53.79 7.90

    Table4

    粒径分布
    样品 D10 D50 D90 体积加权平均值D
    RG 6.31 19.00 56.20 26.29
    RG-CTP (8%) 18.52 54.12 138.89 75.28
    RG-CTP (10%) 18.32 68.94 156.49 81.86
    RG-CTP (12%) 19.93 73.57 168.53 87.07

    Table5

    比表面积与孔容孔径
    样品 比表面积/(m2·g−1) 孔容/(mL·g−1) 孔径/nm
    RG 7.006 0.025 3.815
    RG-CTP (8%) 6.613 0.013 3.762
    RG-CTP (10%) 6.527 0.012 3.355
    RG-CTP (12%) 5.754 0.009 3.354
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