Facile preparation of composite electrodes for supercapacitors by CNT entrapment into carbon matrix derived from pitch at a softening point

We propose a facile route to fabricate carbon nanotube-activated carbon composite electrodes for supercapacitor applications. The crux of our approach lies in the use of softened pitch that becomes viscous at 110 °C and combines effortlessly with multi-walled carbon nanotubes, allowing a one-pot chemical activation at 900 °C. Meso/macroscale pores created by a bundle of the nanotubes can be infiltrated effectively by the softened pitch, increasing the apparent tap density with microporosity. This composite electrode leverages the high electron conductivity of percolated multi-walled carbon nanotubes and the large surface area of activated carbon, leading to high gravimetric (11.9 Wh/kg) and volumetric energy densities (10.4 Wh/L) at 1 mA/cm². Our method substantially simplifies the preparation of carbon nanotube-activated carbon composite materials and can be an excellent strategy to obtain practical energy storage properties at a reduced processing cost.