The composite of 3D carbon nanotube architecture and NiCo double hydroxide for high-performance supercapacitor

Abstract

A three-dimensional porous architecture of multiwalled carbon nanotubes (MWCNT), denoted as 3D-MWCNT, was fabricated on Ni foam (NiF) via a simple hydrothermal method. The 3D-MWCNT, constructed with interlaced carbon nanotubes, is a highly porous network structure and is subsequently used as the electrical conductive platform for the fabrication of positive electrode of faradaic supercapacitor. The obtained positive electrode was denoted as NiCo-DH/3D-MWCNT/NiF, which was produced via the electrodeposition of NiCo double hydroxide (NiCo-DH) on 3D-MWCNT/NiF. The 3D-MWCNT platform not only endows NiCo-DH/3D-MWCNT/NiF large surface area but also enhanced electrical conductivity. NiCo-DH/3D-MWCNT/NiF displays an ultrahigh areal capacity of 6.142 C cm−2 at 60 mA cm−2 and 96.31% capacity retention after 2000 cycles at 60 mA cm−2. An asymmetrical supercapacitor (ASC) is also assembled with NiCo-DH/3D-MWCNT/NiF as the positive electrode and activated carbon (AC) as the negative electrode. The ASC exhibits a prominent specific energy of 30.99 Wh kg−1 at a high specific power of 427.46 W kg−1. It is especially worth noting that the ASC exhibited remarkable capacity retention of 84.7% even after 2000 galvanostatic charge–discharge cycles at a high current density of 30 mA cm−2.