介孔碳微球的氢醌改性及电容性能研究

Hydroquinone-modified Mesoporous Carbon Nanospheres with Excellent Capacitive Performance

由于纯碳材料单一的双电层储能机理,其比电容较低,而赝电容材料可利用法拉第反应进行能量存储,可以获得较高的比电容。作者利用软模板法制备出具有三维有序结构的介孔碳微球,然后采用水热法制备氢醌改性的介孔碳微球。循环伏安和恒流充放电测试表明,氢醌改性使得介孔碳微球不仅具有双电层电容,而且具有赝电容。负载10wt%氢醌的介孔碳微球具有最大的比电容值,当电流密度为0.5 A/g时,其比电容值高达285 F/g;当电流密度增大到10 A/g时,其比电容值仍高达212 F/g,表现出优异的倍率特性。这主要归因于氢醌以π-π堆叠方式负载在碳质介孔表面,不仅提供了额外的赝电容,而且提高了碳材料在水系电解液中的倍率特性。

Pure carbon materials store energy mainly by the electric double-layer mechanism, resulting in their low specific capacitance. However, pseudocapacitive materials can store energy through faradaic reactions, leading to drastically improved specific capacitance. Herein, mesoporous carbon nanospheres with 3D ordered pore symmetry were synthesized by soft template method. Then, the hydroquinone （HQ） was used to modify mesoporous carbon nanospheres by hydrothermal method. As demonstrated by cyclic voltammetry and galvanostatic charge-discharge tests, HQ modified carbon nanospheres show both electric double layer capacitance and pseudocapacitance. Carbon nanospheres with 10wt% HQ loading possess the highest specific capacitance of 285 F/g at the current density of 0.5 A/g and 212 F/g at 10 A/g, exhibiting excellent rate performance. This should be ascribed to the HQ molecules adsorbed on carbonaceous mesopore surface by π-π interactions, which not only provide extra pseudocapacitance, but also improve the rate performance of carbons in aqueous electrolyte.