水热法合成rGO/Mo0.7Co0.3S2超级电容器电极复合材料

Hydrothermal method of rGO/Mo0.7Co0.3S2 nanocomposites for high-performance supercapacitor electrodes

  • 摘要: 氧化石墨烯(rGO)以广泛的比表面积(SSA)(2630 m2/g)、高电导率和化学稳定性及优异的力学、热和光学性能成为超级电容器中的佼佼者,但是氧化石墨烯本身导电性较差,因此本文通过rGO与Mo0.7Co0.3S2复合改善其性能,采用简单的水热法成功合成了rGO与Mo0.7Co0.3S2不同质量比的纳米复合材料rGO/Mo0.7Co0.3S2。通过XRD、SEM、HRTEM、EDS等手段对其物理结构进行表征。以泡沫镍为基底,聚偏氟氯乙烯为粘结剂,N-甲基吡咯烷酮作为辅助剂制作电极,在KOH为电解液的三电极电化学工作站上测试其电化学性能。实验结果表明, rGO/Mo0.7Co0.3S2纳米复合材料为六方结构,结晶良好,形貌主要为纳米花状微球结构,Mo0.7Co0.3S2纳米颗粒表面被一层纱似的rGO包裹着。rGO/Mo0.7Co0.3S2纳米复合材料表现出明显的赝电容行为,特别是rGO/Mo0.7Co0.3S2电极(rGO的含量为30wt%)表现出最大的比电容和最小的扩散阻抗,在电流密度5 A·g−1下循环3000次后rGO/Mo0.7Co0.3S2电极(rGO的含量为30wt%)的比电容值由1377.00 F·g−1降为1307.87 F·g−1,库伦效率为95%,这可能是由于Mo0.7Co0.3S2与rGO之间发生的耦合效应。

     

    Abstract: Graphene oxide (rGO) has become a leader in supercapacitors with a wide specific surface area (SSA) (2630 m2/g), high electrical conductivity and chemical stability, and excellent mechanical, thermal and optical properties. However, rGO itself has poor electrical conductivity, so in this paper, rGO is combined with Mo0.7Co0.3S2 to improve its performance. This paper was successfully synthesized different mass ratios of rGO and Mo0.7Co0.3S2 by a simple hydrothermal method. The microstructure was characterized by XRD, SEM, HRTEM, EDS. The electrode is made by using foamed nickel as the substrate, polyvinylidene chlorofluoride as the binder, and N-methyl pyrrolidone as the auxiliary agent. The electrochemical performance was tested on a three-electrode electrochemical workstation with KOH as the electrolyte. The experimental results show that all samples exhibit hexagonal system structure with good crystallization, the morphologies are flower-like microsphere shape with a certain degree of agglomeration. The surface of Mo0.7Co0.3S2 nanoparticles is wrapped by a layer of rGO like yarn. rGO/Mo0.7Co0.3S2 nanocomposite exhibits pseudo-capacitance behavior and excellent electrochemical performance, especially the Mo0.7Co0.3S2 electrode (30wt% rGO content) exhibits the largest specific capacitance and smallest impedance, and the Mo0.7Co0.3S2 electrode (30wt% rGO content) electrode reduced from 1377.00 F·g−1 to 1307.87 F·g−1 after 3000 cycles at a current density of 5 A·g−1, the coulombic efficiency is 95%, which may be due to the Coupling effect between Mo0.7Co0.3S2 and rGO.

     

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