表面官能团化增强碳纳米笼超级电容器性能

以具有多级孔结构、高比表面积、良好导电性等特征的碳纳米笼（CNCs）为前体，采用硝酸氧化法在CNCs表面引入含氧官能团。以CNCs为超级电容器电极材料，在相同电流密度下，官能团化样品的比电容显著高于纯CNCs；在1A·g^-1下比电容最高可达到255F·g^-1，比纯CNCs的188F·g^-1增加了34%，这表明表面含氧官能团化能够显著提高CNCs的超级电容器比电容。在100A·g^-1的大电流密度下，硝酸氧化后CNCs的比电容保持在111~167F·g^-1，表明具有良好的耐大电流充放电性能。在10A·g^-1的电流密度下循环10000圈后，CNC-6M样品的比电容由196F·g^-1下降到176F·g^-1，样品的比电容仍保留90%，具有良好的循环稳定性。表面含氧官能团化CNCs所表现出的这种优异的超级电容器性能归因于CNCs的多尺度分级孔结构、高比表面积、良好的导电性、表面亲水性含氧官能团化带来的浸润性提高和引入的赝电容。

Enhancement of Supercapacitor Performance of Carbon Nanocages by Surface Functionalization

Oxygen-containing functional groups can be introduced on the surface of carbon nanocages (CNCs) without damaging the skeleton structure. The functionalized CNCs were used as the electrode materials for supercapacitor. The specific capacitance of CNC-6M reached 255 F·g^-1 and increased 34% as compared to 188 F·g^-1 of pristine CNC at a current density of 1 A·g^-1. At the same current density, the specific capacitance of the as-functionalized CNCs was significantly higher than that of pristine CNCs, namely, the surface functionalization for CNCs could obviously enhance the supercapacitors performance. Furthermore, at a high current density of 100 A·g^-1, the specific capacitance of as-oxidized CNCs still retained at a level of 111~167 F·g^-1, i.e., they exhibited good resistance to high current charge and discharge. After 10000 charging-discharging cycles at a current density of 10 A·g^-1, the specific capacitance of CNC-6M only dropped from 196 to 176 F·g^-1, i.e., the functionalized CNCs possessed good cycle stability. The excellent supercapacitor performance of the as-functionalized CNCs is ascribed to the hierarchical pore structure, high surface area, good electrical conductivity of CNCs as well as the improved wettability and pseudocapacitance derived from the oxygen-containing functional groups.