Fabrication and supercapacitive properties of a thick electrode of carbon nanotube-RuO_2 core-shell hybrid material with a high RuO_2 loading

摘要

A core-shell hybrid material of amorphous hydrous RuO_2-coated carbon nanotubes (CNT-RuO_2) with a RuO_2 loading as high as 82.4wt% was prepared by a solution method using RuCl_3 and NaHCO_3 aqueous solutions. The effect of preparation conditions, especially the dripping speed of the NaHCO_3 solution, on the formation of the core-shell structure was investigated, and the corresponding mechanism was discussed. Supercapacitive properties of the CNT-RuO_2 and amorphous hydrous RuO_2 electrodes with a thickness of over 200μm were studied and the crucial factors to govern their rate capability were analyzed. For the thick CNT-RuO_2 electrode, a comparison of its specific capacitance before and after subtracting the effect of the voltage drop of discharge curves caused by the inner resistance of the CNT-RuO_2 symmetrical supercapacitor indicates that electronic conductivity is more important than proton diffusion in determining its rate capability.