High Performance of Electrochemically Deposited NiCo₂S₄/CNT Composites on Nickel Foam in Flexible Asymmetric Supercapacitors

Abstract

To exploit an efficient supercapacitor, improving the comprehensive properties of electrode materials has become an important goal. In this work, NiCo 2 S 4 nanosheets were successfully combined with highly conductive carboxylated carbon nanotubes (CNT-h-COOH) by electrochemical deposition, forming an interconnected porous network of NiCo 2 S 4 nanosheets/CNT composite on the nickel foam. The results showed that the deposition potential and time played important roles to influence the morphology and electrochemical performance of NiCo 2 S 4 nanosheets/CNT composite. It turned out that the NiCo 2 S 4 / CNT composite prepared by depositing at a −0.9 V for 10 min presented excellent specific capacity at 1 A g −1 (2498.12 F g −1 ), outstanding rate characteristic at 100 A g −1 (compared with 1 A g −1 , the capacitance retention was 61.1%), and exceptional cycle performance at 20 A g −1 (the capacitance retention rate after 10 000 charge/discharge cycles was 96.08%). Further, the flexible asymmetric supercapacitor (ASC) with a poly(vinyl alcohol) (PVA)/KOH gel electrolyte was obtained using commercial activated carbon as the anode and the NiCo 2 S 4 /CNT composite as the cathode. The ASC showed a high specific capacity of 215.06 F g −1 at 0.25 A g −1 , an exceptional capacitance retention rate of 89.03% after 10 000 cycles, an outstanding energy density of 76.47 Wh kg −1 at 201.01 W kg −1 , and excellent flexibility. Thereby, our study demonstrated that the electrodeposited porous NiCo 2 S 4 /CNT composite possesses a broad potential application in the area of supercapacitors.

Nickel–Cobalt Sulfide Nanosheets Anchored on Porous Carbon for Energy Storage and Small-Molecule Detection

“…Two satellite peaks are also observed at 860.4 and 879.6 eV . Similarly, the Co 2p spectrum in Figure b is assigned to Co 3+ (794.7 and 779.7 eV) and Co 2+ (799.2 and 780.9 eV), with two satellite peaks located at 803.4 and 782.6 eV . The S 2p spectrum has two peaks at 163.1 and 162.0 eV for S 2p 1/2 and S 2p 3/2 , respectively, and a weak satellite peak at 169.6 eV (Figure c) .…”

“…21 Similarly, the Co 2p spectrum in Figure 5b is assigned to Co 3+ (794.7 and 779.7 eV) and Co 2+ (799.2 and 780.9 eV), with two satellite peaks located at 803.4 and 782.6 eV. 22 The S 2p spectrum has two peaks at 163.1 and 162.0 eV for S 2p 1/2 and S 2p 3/2 , respectively, and a weak satellite peak at 169.6 eV (Figure 5c). 20 Furthermore, the C 1s spectrum is deconvoluted into four peaks for C−S (284.0 eV), C−C (284.8 eV), C−N (285.8 eV), and O�C−O (287.0 eV) (Figure 5d).…”

Recent advances in Ni-materials/carbon nanocomposites for supercapacitor electrodes

“…The electrochemical properties of supercapacitors on the basis of Ni materials and CNTs composite electrodes are reported in Table 2 144–163 The nanocomposite CNTs/NiCo 2 S 4 showed remarkable capacitive properties. In the structure of the asymmetric supercapacitor, it exhibited energy and power densities of 43.3 W h kg −1 and 800 W kg −1 .…”

“…Ternary nickel cobalt sulfide/oxides and carbon nanotube composites. The electrochemical properties of supercapacitors on the basis of Ni materials and CNTs composite electrodes are reported in Table 2 [144][145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161][162][163] The nanocomposite CNTs/NiCo 2 S 4 showed remarkable capacitive properties. In the structure of the asymmetric supercapacitor, it exhibited energy and power densities of 43.3 W h kg À1 and 800 W kg À1 .…”

CNTs-Supercapacitors: A Review of Electrode Nanocomposites Based on CNTs, Graphene, Metals, and Polymers

“…As can be observed from Figure 3, the electrode nanocomposite based on the CNTs/graphene, CNTs/metal, and CNTs/polymer are more highlighted in the co-occurrence keywords analysis. Other characterizations such as symmetric [9][10][11], flexible [12,13], wearable electronic [14,15], cellulose [16][17][18], cycling stability [19,20], pseudocapacitor [21,22], solid-state supercapacitor [23][24][25], activated carbon [26][27][28], polymers [29][30][31], MXene [32,33], and CNTs [34][35][36][37][38][39][40][41][42][43][44][45][46] were mentioned in Figure 3. Nanomaterials are widely used for industrial applications such as supercapacitors, batteries, antibacterial activity, nano-membranes, and sensors [47][48][49][50][51][52]…”