Potassium chloride-catalyzed growth of porous carbon nanotubes for high-performance supercapacitors

Porous carbon nanotubes with unique structure is an ideal electrode material for supercapacitors. However, the synthesis of porous carbon nanotubes requires expensive catalysts such as heavy metals or heavy metal salts, which limits their wider application. To solve the problem, a one-step high-temperature potassium chloride-catalyzed strategy is proposed to directly grow porous carbon nanotubes. Magnesium reacts with carbon dioxide to form carbon as the carbon source and magnesium oxide that can form porosity of carbon nanotubes. Low-cost and recyclable potassium chloride can replaced expensive heavy metals or heavy metal salts to catalyze the growth of porous carbon nanotubes. The obtained porous carbon nanotube (CC-KCl-700) show great advantages in structure and delivers excellent electrochemical properties and its specific capacitance reaches up to 334.4 F g−1. After 10,000 cycles at 10 A g−1, the capacitance of the CC-KCl-700 still reaches to 230 F g−1. Beside, the assembled symmetric supercapacitor with a high energy density and great rate performance can successfully provide energy for devices.