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    FCC油浆基高软化点沥青包覆天然石墨负极材料的电化学性能

    Electrochemical Property of Natural Graphite Anode Coated with High Softening Point Pitch Derived from FCC Oil Slurry

    • 摘要: 天然石墨来源广泛、成本低廉,并且具有相对较高的比容量以及稳定的嵌/脱锂电位,是目前商业化锂离子电池负极的主要材料。但其存在与有机电解液相容性差,溶剂共嵌入导致石墨层剥离,因而库仑效率和循环性能不理想等问题。本文以催化裂化油浆为原料,通过空气吹扫-氮气氛围热缩聚的方法制备高软化点沥青,并将其作为包覆剂,通过液相包覆的方法改性天然石墨材料。结果表明,沥青包覆量为10%时可以在天然石墨表面形成完整的包覆层,降低比表面积,从而改善天然石墨材料的循环性能和倍率性能,所得的包覆石墨材料在0.5 C下循环200次时容量保持率由69.01%提高到88.53%,展现出较佳的电化学性能。

       

      Abstract: Natural graphite, characterized by its wide availability, low cost, relatively high specific capacity, and stable intercalation/deintercalation potential, is the primary anode material for commercial lithium-ion batteries. However, its intrinsic surface defects and poor compatibility with organic electrolytes often lead to significant degradation in reversible specific capacity, primarily due to solvent co-intercalation and consequent graphite layer exfoliation, resulting in unsatisfactory Coulombic efficiency and cycling performance. Surface modification represents an effective strategy to address these limitations. Pitch, an important by-product of the petroleum refining industry, is widely utilized as a coating material for graphite modification. Upon high-temperature cracking in an inert atmosphere, the pitch coating seals surface defects and forms an amorphous carbon shell on the graphite surface. This resulting core-shell structure effectively enhances the reversible specific capacity and cycling stability of graphite. In this study, high-softening-point pitch was synthesized from fluid catalytic cracking oil slurry via air purging under a nitrogen atmosphere followed by thermal polycondensation. This pitch was then employed as a coating agent to modify natural graphite through a liquid-phase coating process. Results indicate that a 10%(mass fraction) pitch coating forms a complete layer on the natural graphite surface, reducing its specific surface area and thereby improving both cycling and rate performance. The coated graphite exhibits a significantly enhanced capacity retention rate of 88.53% after 200 cycles at 0.5 C, compared to 69.01% for the pristine material, demonstrating superior electrochemical performance.

       

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