采用直流电弧法,在CH4气氛下以钨棒为阴极蒸发锰镍混合物阳极靶材,制备了(Mn7C3,Ni)@C纳米粒子,并用作超级电容器电极材料.(Mn7C3,Ni)@C纳米粒子具有明显的核壳结构,平均粒径50 nm.在碳外壳包覆下,内核为Mn7C3和Ni的混合物.镍有催化作用,促进碳源形成,影响C壳厚度,锰容易与碳结合生成具有赝电容特性的Mn7C3.镍因其催化作用促进碳壳成长,使纳米粒子具有双电子层电容.Mn-C化合形成的Mn7C3具有赝电容特性.因此,不同锰镍比例对电极电化学性能有极大影响:锰比例越高,材料比电容越好(485.12 F/g),但循环寿命随之变差;镍比例越高,材料循环稳定性越好(303.57 F/g),1000次循环后其比电容保持为原来的70％.
(Mn7C3,Ni)@C nanoparticles were synthesized for electrode material in a supercapacitor.Using DC arc-discharge method,in which the anodic target of Ni-Mn mixture was evaporated in the methane atmosphere by a tungsten cathode.The prepared nanoparticles own a well-defined core/shell structure with average diameter of 50 nm.Encapsulated inside of the carbon shell,the core of the nanoparticles is composed of Mn7C3 and Ni.Owing to its catalytic effect,Ni promotes the growth of carbon shell which has the typical double-layer capacitance.Meanwhile Mn7C3 as the product of Mn-C reaction is able to provide pseudo-capacitance.The proportion of Ni-Mn in the nanoparticles consequently affects the overall electrochemical performance of the electrodes.The specific capacitance of the electrode increases with the promotion of Mn content (485.12 F/g).The results shows that the nanoparticles with more Ni have better cycle stability (303.57 F/g) and retain 70％ of the initial capacitance after 1000 cycles.
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