Supercapacitor Performance of NiO, NiO-MWCNT, and NiO–Fe-MWCNT Composites

Abstract

The NiO-CNT and NiO–Fe-CNT composites that have been prepared from waste high density polyethylene plastic and their carbon nanotube (CNT) quality-dependent supercapacitance tuning have been reported here. Multiwalled CNT (MWCNT) formation has been confirmed from TEM and Raman spectra with an I D/I G ratio of 0.77, which stands for high graphitization. The specific surface area (SSA) of MWCNTs in the NiO–Fe-CNT composite was 87.8 m2/g, while in the NiO-CNT composite, it was 25 m2/g. NiO–Fe-CNT displayed higher specific capacitance and energy density (1360 Fg–1 and 1180 W h kg–1) than NiO-CNT (1250 Fg–1 and 1000 W h kg–1), which may be due to the presence of higher-quality MWCNTs in the NiO–Fe-CNT composite. NiO–Fe-CNT displayed higher contributions of electric double-layer capacitor (59%) behavior compared to NiO-CNT (38%) and represented a hybrid supercapacitor. NiO–Fe-CNT also displayed a capacitive retention of 96% after 1000 charge–discharge cycles. Furthermore, studies in acidic electrolytes revealed higher performance of NiO–Fe-CNT than NiO-CNT, displaying specific capacitances of NiO–Fe-CNT to be 1147 Fg–1 in 2 M H2SO4 and 943 Fg–1 in 2 M HCl. It has been qualitatively explored that the quality of CNTs, SSA, and quantum confinement effects in the composites may be the factors responsible for the performance difference in NiO–Fe-CNT and NiO-CNT. The present work is geared toward the low-cost fabrication of high-quality CNT composites for supercapacitors and energy storage applications. The present work also contributes quantitatively to the understanding of CNT quality as an important parameter for the performance of CNT-composite-based supercapacitors.

Unlocking the synergetic potential of cobalt iron phosphate and multiwalled carbon nanotube composites towards supercapacitor application

“…2 Although conventional carbon-based SCs exhibit superior power output and endurance, their lower energy density and restricted energy storage capability limit their industrial application potential. 3–5 Recently, there has been a lot of interest in supercapacitors due to the increasing need for portable and wearable electronics. These gadgets have several desirable qualities, such as being lightweight, having good mechanical qualities, and being environmentally friendly.…”

Studies on improved stability and electrochemical activity of metal oxides/sulfides‐based polymer nanocomposites for energy storage applications

“…29 It was reported that the higher-quality MWCNTs in the NiO-Fe-CNT composite is the reason for the higher specific capacitance and energy density (1360 F g À1 and 1180 W h kg À1 ) that NiO-Fe-CNT exhibited compared to NiO-CNT (1250 F g À1 and 1000 W h kg À1 ). 30 To address this issue, some researchers attempted to mix metal sulfides and oxides to enhance the electrical conductivity, high stability, low cost, energy and power densities. Fabrication of NiS/NiO electrode with enhanced capacitance of 1260 F g À1 at 0.5 A g À1 with 93% retention after 30,000 cycles was reported.…”

Film Thickness Effect in Restructuring NiO into LiNiO2 Anode for Highly Stable Lithium-Ion Batteries

“…After 600 cycles, this anode material delivered a high capacity of ~1900 mAh g −1 , which is much higher than the theoretical capacity of ~1000 mAh g −1 . The NiO nanostructure also received great attention for its various electrical/optical applications, including capacitors, gas sensors, solar cells, and magnetic applications [36][37][38][39][40]. NiO has a theoretical capacity of ~720 mAh g −1 , which is more than twice that of graphene [41].…”