水热法合成rGO/Mo_(0.7)Co_(0.3)S_(2)超级电容器电极复合材料

Hydrothermal method of rGO/Mo_(0.7)Co_(0.3)S_(2) nanocomposites for high-performance supercapacitor electrodes

氧化石墨烯(rGO)以广泛的比表面积(SSA)(2630 m^(2)/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Mo_(0.7)Co_(0.3)S_(2)复合改善其性能,采用简单的水热法成功合成了rGO与Mo_(0.7)Co_(0.3)S_(2)不同质量比的纳米复合材料rGO/Mo_(0.7)Co_(0.3)S_(2)。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/Mo_(0.7)Co_(0.3)S_(2)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,Mo_(0.7)Co_(0.3)S_(2)纳米颗粒表面被一层纱似的rGO包裹着。rGO/Mo_(0.7)Co_(0.3)S_(2)纳米复合材料表现出明显的赝电容行为,特别是rGO/Mo_(0.7)Co_(0.3)S_(2)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/Mo_(0.7)Co_(0.3)S_(2)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)^(-1),库伦效率为95%,这可能是由于Mo_(0.7)Co_(0.3)S_(2)与rGO之间发生的耦合效应。

Graphene oxide(rGO) has become a leader in supercapacitors with a wide specific surface area(SSA)(2 630 m^(2)/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 Mo_(0.7)Co_(0.3)S_(2)to improve its performance. This paper was successfully synthesized different mass ratios of rGO and Mo_(0.7)Co_(0.3)S_(2)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 Mo_(0.7)Co_(0.3)S_(2)nanoparticles is wrapped by a layer of rGO like yarn. rGO/Mo_(0.7)Co_(0.3)S_(2)nanocomposite exhibits pseudo-capacitance behavior and excellent electrochemical performance, especially the Mo_(0.7)Co_(0.3)S_(2)electrode(30wt% rGO content) exhibits the largest specific capacitance and smallest impedance, and the Mo_(0.7)Co_(0.3)S_(2)electrode(30wt% rGO content) electrode reduced from 1 377.00 F·g^(-1)-1 to 1 307.87 F·g^(-1)after 3 000cycles at a current density of 5 A·g^(-1), the coulombic efficiency is 95%, which may be due to the Coupling effect between Mo_(0.7)Co_(0.3)S_(2)and rGO.