界面自组装构筑空心多孔石墨化炭球及其电化学性能

An interfacial self-assembly strategy to fabricate graphitic hollow porous carbon spheres for supercapacitor electrodes

  • 摘要: 独特的空腔结构、丰富的比表面积以及良好的导电性使得空心多孔石墨化炭球在储能领域显示了巨大的应用潜力。通过单宁酸与铁离子的络合作用以及三草酸合铁酸钾的活化和石墨化作用,采用一步炭化法成功制备了空心多孔石墨化炭球,并研究了炭化温度对炭球结构形貌的影响。基于高比表面积、快速的离子扩散通道以及低电阻的石墨化结构,空心多孔石墨化炭球表现出优异的电化学性能。在电流密度为1 A g−1时,比电容达到332.7 F g−1。组装成对称超级电容器在1 mol L−1 Na2SO4电解液中,当功率密度为459.1 W kg−1时,能量密度达到23.7 Wh kg−1,且经10000次循环以后,电容量保持为92.1%。本研究不仅为构筑多孔石墨化炭球提供了一种方法简单、成本较低的无模板自组装法,而且为设计和优化炭球中离子和电子的传输提供了一定的参考价值。

     

    Abstract: Graphitic hollow porous carbon spheres (GHPCSs) have the advantages of a unique cavity structure, high surface area and excellent conductivity, and are promising electrode materials for energy storage. A Fe–tannic acid (TA) framework synthesized using TA as the carbon source and K3 Fe(C2O4)3 as a complexing agent, was self-assembled onto a melamine foam, which was converted to GHPCSs by carbonization, where the K3 Fe(C2O4) 3 also acts as an activating-graphitizing agent. The outer shell of the as-prepared GHPCSs has a large specific surface area, a micropore-dominated structure and excellent electrical conductivity, which ensure a large enough active surface area for charge accumulation and fast ion/electron transport in the partially graphitized carbon framework and pores. The optimum GHPCS has a high capacitance of 332.7 F g−1 at 1 A g−1. An assembled symmetric supercapacitor has a high energy density of 23.7 Wh kg−1 at 459.1 W kg−1 in 1 mol L-1 Na2SO4. In addition, the device has long-term cycling stability with a 92.1% retention rate after 10 000 cycles. This study not only provides an economic and time-saving approach for constructing GHPCSs by a self-assembly method, but also optimizes ion/electron transport in the carbon spheres to give them excellent performance in capacitive energy storage.

     

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