毛细管破裂法制备中间相炭微球及其电化学性能

An innovative and efficient method for the preparation of mesocarbon microbeads and their use in the electrodes of lithium ion batteries and electric double layer capacitors

  • 摘要: 基于沥青在熔融纺丝过程中的滴落行为和流变学理论,提出了一种新型高效的中间相炭微球(MCMB)制备方法—毛细管破裂法(DCB法)。本实验以中间相沥青为原料,采用DCB法考察了不同接收相(水或THF)对MCMB制备的影响规律,并系统研究了相应MCMB微观结构的演变规律。在此基础上,所制MCMB经750 °C的KOH活化制备了A-MCMB,以及经2800 °C的石墨化制备了G-MCMB,并分别探究了它们作为超级电容器(EDLC)和锂离子电池(LIB)电极材料的电化学性能。结果表明:采用DCB方法所制备的水接收相的MCMB-W和THF接收相的MCMB-T均呈现尺寸约1~2 μm的球形结构特征。此外,A-MCMB-T具有高比表面积1391 m2 g−1、微孔体积0.55 cm3 g−1和中孔体积0.24 cm3 g−1,作为EDLC的电极材料时,其比电容比MP衍生的炭材料提高了30%,且电容保持率也显著提升。同时,G-MCMB-T具有较高的石墨化度0.895和有序的层状结构,作为LIB的负极材料时,在100 mA g−1下进行100次循环后,具有353.5 mAh g−1的高比容量。因此,本文提出并验证了一种新的MCMB制备方法,有望为储能材料的设计和开发提供了一种思路和途径。

     

    Abstract: An innovative and efficient method for preparation of mesocarbon microbeads (MCMBs) was developed based on the dripping behavior and rheological properties of molten pitch during melt-spinning, where a string of beads was formed after the pitch was extruded from spinnerets and dropped into a receiving solvent (tetrohydrofuran or water). The pitch droplets were first carbonized, then activated by KOH or graphitized at 2800 °C to prepare A-MCMBs or G-MCMBs, respectively, and these were respectively used as the electrode materials for electric double layer capacitors (EDLCs) and lithium-ion batteries (LIBs). Results showed that both MCMB-W prepared using water as the receiving solvent and MCMB-T prepared using tetrohydrofuran as the receiving solvent had a spherical shape with sizes of 1-2 μm. A-MCMB-T had a high specific surface area (1 391 m2 g−1), micropore volume (0.55 cm3 g−1) and mesopore volume (0.24 cm3 g−1), with a 30% higher specific capacitance than an activated mesophase carbon prepared under the same conditions, and its capacitance retention was significantly improved when it was used as an electrode material for EDLCs. G-MCMB-T had a high degree of graphitization (0.895) and when it was used as an electrode material for LIBs it had a high specific capacity of 353.5 mAh g−1 after 100 cycles at 100 mA g−1. This work reports a new preparation method for MCMBs, which could be used to prepare energy storage materials.

     

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