氮掺杂纳米碳包覆MnO复合材料的制备与电化学性能

Preparation and Electrochemical Performance of Nitrogen-Doped Nanocarbon Coated MnO Composites

利用静电引力在MnO_(2)纳米线表面吸附盐酸处理的三聚氰胺(H-melamine),H-melamine和MnO_(2)纳米线的质量比分别为1∶1,3∶1,5∶1,然后进行退火以制备氮掺杂纳米碳包覆MnO(MnO@N-C)复合材料,研究了复合材料的物相组成、微观结构和电化学性能。结果表明:退火处理使得MnO_(2)纳米线和包覆在其表面的H-melamine分别转变为MnO及氮掺杂碳材料,得到的MnO@N-C复合材料呈现串珠状形貌;当H-melamine与MnO_(2)纳米线的质量比为3∶1时,复合材料的电化学性能最佳,在1 A·g^(-1)电流密度下表现出1050 F·g^(-1)的超高比电容,并且在3 A·g^(-1)电流密度下经6000次充放电循环后具有75%的容量保持率。以复合材料为正极、活性炭为负极组装的锌离子混合超级电容器的工作电压范围可达0~2.0 V,且表现出72 W·h·kg^(-1)的能量密度;在3 A·g^(-1)的电流密度下经过5000次循环后,超级电容器仍能保持88%的初始比电容。

Assisted by electrostatic force,MnO_(2)nanowires were hybridized with hydrochloric acid treated melamine(H-melamine),with mass ratios of H-melamine to MnO_(2)nanowires of 1∶1,3∶1 and 5∶1,respectively,and then was annealed to fabricate nitrogen-doped nanocarbon coated MnO(MnO@N-C)composites.The phase composition,microstructure and electrochemical performance of the composite were studied.The results show that the MnO_(2)nanowires and surface-coated H-melamine were transformed to MnO and nitrogen-doped carbon materials,respectively,by annealing,and the obtained MnO@N-C composite showed beadlike morphology.When the mass ratio of H-melamine to MnO_(2)nanowires was 3∶1,the composite achieved the best electrochemical performance,exhibiting high specific capacitance of 1050 F·g^(-1)at the current density of 1 A·g^(-1)and capacitance retention of 75%after 6000 charge/discharge cycles at 3 A·g^(-1)current density.The zinc-ion hybrid supercapacitor assembled with the composite as cathode and activated carbon as anode could operate in the voltage window of 0-2.0 V,and showed an energy density of 72 W·h·kg^(-1).After 5000 cycles at the current density of 3 A·g^(-1),the supercapacitor still maintained 88%of the initial specific capacitance.