N掺杂石墨化纳米金刚石超级电容器电极材料性能

Properties of N-doped graphitized nano diamond electrode materials for supercapacitors

为探索制备高能量密度和高循环性能的超级电容器材料,将三聚氰胺与石墨化纳米金刚石(graphitized nano diamond,GND)混合物在N2气氛中高温处理,制备表面N掺杂吸附的核壳纳米复合粒子(nitrogen doped GND,N-GND)。由拉曼光谱和X射线衍射分析可知:N原子掺入石墨层中,在一定程度上增加其缺陷,且不改变其晶体结构。由透射电镜分析可知:N掺杂引起GND周围石墨层出现蜷曲形状。对N-GND粉末电极进行电化学性能测试,结果表明:在扫速为5 mV/s时,电极比电容高达206.7 F/g;在对称两电极体系下的恒流充放电测试中,在电流密度为0.4 A/g时,N-GND的比电容达到198.7 F/g;在50 mV/s的扫描速度下,经2000圈循环伏安测试后,比电容仅衰减4.23%,表现出优异的循环稳定性。以N-GND作为新型超级电容器电极材料,掺杂吸附的石墨壳层赋予其良好的导电性,GND芯部具有高热稳定性及化学稳定性,可避免传统石墨烯叠聚问题并构造可控的介孔通道,同时N掺杂吸附可提高其电容性能。

The mixture of melamine and graphitized nano diamond(GND)was used to prepare super capacitor materials with high energy density and high cycle performance.The raw material was treated at high temperature in nitrogen atmosphere to prepare the core-shell nanocomposites of N-doped graphene(N-GND).Raman spectroscopy and X-ray diffraction analysis showed that the addition of N atoms into the graphite layer increased the defects in the graphite layer to a certain extent without changing its crystal structure.TEM analysis showed that N-doping caused the curl shape of graphite layer around GND.The electrochemical performance of N-GND electrode was tested.Results showed that the specific capacitance of the electrode was 206.7 F/g at 5 mV/s.In the constant-current charge-discharge test of symmetrical two-electrode system,the specific capacitance of N-GND was 198.7 F/g at 0.4 A/g.The specific capacitance attenuated only 4.23%even after 2000 cycles of CV,indicating excellent cyclic stability of the electrode at 50 mV/s.N-GND,as the electrode material of a new supercapacitor,had good conductivity due to its graphene shell and high thermal and chemical stability for the GND core.It could also avoid the stacking problem of traditional graphene and construct controllable mesoporous channels.In addition,N-doping would improve the capacitance performance.