scholarly journals Facile synthesis of NiCo 2 S 4 /CNTs nanocomposites for high-performance supercapacitors

2018 ◽  
Vol 5 (9) ◽  
pp. 180953 ◽  
Author(s):  
Yunxia Huang ◽  
Ming Cheng ◽  
Zhongcheng Xiang ◽  
Yimin cui

Herein, porous NiCo 2 S 4 /CNTs nanocomposites were synthesized via a simple hydrothermal method followed by the sulphurization process using different sulfide sources. By comparing two different sulfur sources, the samples using thioacetamide as sulfide source delivered more remarkable electrochemical performance with a high specific capacitance of 1765 F g −1 at 1 A g −1 and an admirable cycling stability with capacitance retention of 71.7% at a high current density of 10 A g −1 after 5000 cycles in 2 M KOH aqueous electrolyte. Furthermore, an asymmetric supercapacitor (ASC) device was successfully fabricated with the NiCo 2 S 4 /CNTs electrode as the positive electrode and graphene as the negative electrode. The device provided a maximum energy density of 29.44 W h kg −1 at a power density of 812 W kg −1 . Even at a high power density of 8006 W kg −1 , the energy density still reaches 16.68 W h kg −1 . Moreover, the ASC presents 89.8% specific capacitance retention after 5000 cycles at 5 A g −1 . These results reveal its great potential for supercapacitors in electrochemical energy storage field.

2018 ◽  
Vol 47 (47) ◽  
pp. 17146-17152 ◽  
Author(s):  
Xiao Liang ◽  
Qiufan Wang ◽  
Yun Ma ◽  
Daohong Zhang

A two-ply CNT yarn asymmetric supercapacitor was fabricated by assembling a CuCo2O4 nanowire positive electrode and a PPy nanoparticle negative electrode. The full cell exhibits a high specific capacitance of 59.55 mF cm−2 and a high energy density of 0.02 mW h cm−2.


Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1143 ◽  
Author(s):  
Anil Yedluri ◽  
Tarugu Anitha ◽  
Hee-Je Kim

Hierarchical NiMoO4/NiMoO4 nanoflowers were fabricated on highly conductive flexible nickel foam (NF) substrates using a facile hydrothermal method to achieve rapid charge-discharge ability, high energy density, long cycling lifespan, and higher flexibility for high-performance supercapacitor electrode materials. The synthesized composite electrode material, NF/NiMoO4/NiMoO4 with a nanoball-like NF/NiMoO4 structure on a NiMoO4 surface over a NF substrate, formed a three-dimensional interconnected porous network for high-performance electrodes. The novel NF/NiMoO4/NiMoO4 nanoflowers not only enhanced the large surface area and increased the electrochemical activity, but also provided an enhanced rapid ion diffusion path and reduced the charge transfer resistance of the entire electrode effectively. The NF/NiMoO4/NiMoO4 composite exhibited significantly improved supercapacitor performance in terms of a sustained cycling life, high specific capacitance, rapid charge-discharge capability, high energy density, and good rate capability. Electrochemical analysis of the NF/NiMoO4/NiMoO4 nanoflowers fabricated on the NF substrate revealed ultra-high electrochemical performance with a high specific capacitance of 2121 F g−1 at 12 mA g−1 in a 3 M KOH electrolyte and 98.7% capacitance retention after 3000 cycles at 14 mA g−1. This performance was superior to the NF/NiMoO4 nanoball electrode (1672 F g−1 at 12 mA g−1 and capacitance retention 93.4% cycles). Most importantly, the SC (NF/NiMoO4/NiMoO4) device displayed a maximum energy density of 47.13 W h kg−1, which was significantly higher than that of NF/NiMoO4 (37.1 W h kg−1). Overall, the NF/NiMoO4/NiMoO4 composite is a suitable material for supercapacitor applications.


2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiaona Wang ◽  
Zhenyu Zhou ◽  
Zhijian Sun ◽  
Jinho Hah ◽  
Yagang Yao ◽  
...  

Abstract Coaxial fiber-shaped supercapacitors are a promising class of energy storage devices requiring high performance for flexible and miniature electronic devices. Yet, they are still struggling from inferior energy density, which comes from the limited choices in materials and structure used. Here, Zn-doped CuO nanowires were designed as 3D framework for aligned distributing high mass loading of MnO2 nanosheets. Zn could be introduced into the CuO crystal lattice to tune the covalency character and thus improve charge transport. The Zn–CuO@MnO2 as positive electrode obtained superior performance without sacrificing its areal and gravimetric capacitances with the increasing of mass loading of MnO2 due to 3D Zn–CuO framework enabling efficient electron transport. A novel category of free-standing asymmetric coaxial fiber-shaped supercapacitor based on Zn0.11CuO@MnO2 core electrode possesses superior specific capacitance and enhanced cell potential window. This asymmetric coaxial structure provides superior performance including higher capacity and better stability under deformation because of sufficient contact between the electrodes and electrolyte. Based on these advantages, the as-prepared asymmetric coaxial fiber-shaped supercapacitor exhibits a high specific capacitance of 296.6 mF cm−2 and energy density of 133.47 μWh cm−2. In addition, its capacitance retention reaches 76.57% after bending 10,000 times, which demonstrates as-prepared device’s excellent flexibility and long-term cycling stability.


Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1750
Author(s):  
Deepa Guragain ◽  
Romakanta Bhattarai ◽  
Jonghyun Choi ◽  
Wang Lin ◽  
Ram Krishna Gupta ◽  
...  

For electrochemical supercapacitors, nickel cobaltite (NiCo2O4) has emerged as a new energy storage material. The electrocapacitive performance of metal oxides is significantly influenced by their morphology and electrical characteristics. The synthesis route can modulate the morphological structure, while their energy band gaps and defects can vary the electrical properties. In addition to modifying the energy band gap, doping can improve crystal stability and refine grain size, providing much-needed surface area for high specific capacitance. This study evaluates the electrochemical performance of aluminum-doped Ni1−xAlxCo2O4 (0 ≤ x ≤ 0.8) compounds. The Ni1−xAlxCo2O4 samples were synthesized through a hydrothermal method by varying the Al to Ni molar ratio. The physical, morphological, and electrochemical properties of Ni1−xAlxCo2O4 are observed to vary with Al3+ content. A morphological change from urchin-like spheres to nanoplate-like structures with a concomitant increase in the surface area, reaching up to 189 m2/g for x = 0.8, was observed with increasing Al3+ content in Ni1−xAlxCo2O4. The electrochemical performance of Ni1−xAlxCo2O4 as an electrode was assessed in a 3M KOH solution. The high specific capacitance of 512 F/g at a 2 mV/s scan rate, 268 F/g at a current density of 0.5 A/g, and energy density of 12.4 Wh/kg was observed for the x = 0.0 sample, which was reduced upon further Al3+ substitution. The as-synthesized Ni1−xAlxCo2O4 electrode exhibited a maximum energy density of 12.4 W h kg−1 with an outstanding high-power density of approximately 6316.6 W h kg−1 for x = 0.0 and an energy density of 8.7 W h kg−1 with an outstanding high-power density of approximately 6670.9 W h kg−1 for x = 0.6. The capacitance retention of 97% and 108.52% and the Coulombic efficiency of 100% and 99.24% were observed for x = 0.0 and x = 0.8, respectively. First-principles density functional theory (DFT) calculations show that the band-gap energy of Ni1−xAlxCo2O4 remained largely invariant with the Al3+ substitution for low Al3+ content. Although the capacitance performance is reduced upon Al3+ doping, overall, the Al3+ doped Ni1−xAlxCo2O4 displayed good energy, powder density, and retention performance. Thus, Al3+ could be a cost-effective alternative in replacing Ni with the performance trade off.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1433 ◽  
Author(s):  
Ahmed S. F. M. Asnawi ◽  
Shujahadeen B. Aziz ◽  
Muaffaq M. Nofal ◽  
Muhamad H. Hamsan ◽  
Mohamad A. Brza ◽  
...  

In this study, the solution casting method was employed to prepare plasticized polymer electrolytes of chitosan (CS):LiCO2CH3:Glycerol with electrochemical stability (1.8 V). The electrolyte studied in this current work could be established as new materials in the fabrication of EDLC with high specific capacitance and energy density. The system with high dielectric constant was also associated with high DC conductivity (5.19 × 10−4 S/cm). The increase of the amorphous phase upon the addition of glycerol was observed from XRD results. The main charge carrier in the polymer electrolyte was ion as tel (0.044) < tion (0.956). Cyclic voltammetry presented an almost rectangular plot with the absence of a Faradaic peak. Specific capacitance was found to be dependent on the scan rate used. The efficiency of the EDLC was observed to remain constant at 98.8% to 99.5% up to 700 cycles, portraying an excellent cyclability. High values of specific capacitance, energy density, and power density were achieved, such as 132.8 F/g, 18.4 Wh/kg, and 2591 W/kg, respectively. The low equivalent series resistance (ESR) indicated that the EDLC possessed good electrolyte/electrode contact. It was discovered that the power density of the EDLC was affected by ESR.


Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 777 ◽  
Author(s):  
Lei Geng ◽  
Fengfeng Yan ◽  
Chenhao Dong ◽  
Cuihua An

Bimetallic oxides have been considered as potential candidates for supercapacitors due to their relatively high electric conductivity, abundant redox reactions and cheapness. However, nanoparticle aggregation and huge volume variation during charging-discharging procedures make it hard for them to be applied widely. In this work, one-dimensional (1D) MnFe2O4@C nanowires were in-situ synthesized via a simply modified micro-emulsion technique, followed by thermal treatment. The novel 1D and core-shell architecture, and in-situ carbon coating promote its electric conductivity and porous feature. Due to these advantages, the MnFe2O4@C electrode exhibits a high specific capacitance of 824 F·g−1 at 0.1 A·g−1 and remains 476 F·g−1 at 5 A·g−1. After 10,000 cycles, the capacitance retention of the MnFe2O4@C electrode is up to 93.9%, suggesting its excellent long-term cycling stability. After assembling with activated carbon (AC) to form a MnFe2O4@C//AC device, the energy density of this MnFe2O4@C//AC device is 27 W·h·kg−1 at a power density of 290 W·kg−1, and remains at a 10 W·h·kg−1 energy density at a high power density of 9300 W·kg−1.


2014 ◽  
Vol 16 (33) ◽  
pp. 17936-17942 ◽  
Author(s):  
Lei Yu ◽  
Nannan Shi ◽  
Qi Liu ◽  
Jun Wang ◽  
Bin Yang ◽  
...  

A novel sandwich-like structured Co–Al LDH–CNT composite has been successfully synthesized. The as-prepared Co–Al LDHs–CNTs composite exhibites a high specific capacitance and a good cycle stability over 2000 cycles


NANO ◽  
2020 ◽  
Vol 15 (10) ◽  
pp. 2050136
Author(s):  
Xuan Zheng ◽  
Xingxing He ◽  
Jinlong Jiang ◽  
Zhengfeng Jia ◽  
Yu Li ◽  
...  

In this paper, the Ni[Formula: see text]Co[Formula: see text]S4@CNTs nanocomposites containing different carbon nanotubes (CNT) content were prepared by a one-step hydrothermal method. More hydroxyl and carboxyl groups were introduced on the surface of CNTs by acidizing treatment to increase the dispersion of CNTs. The acid-treated CNTs can more fully compound with Ni[Formula: see text]Co[Formula: see text]S4 nanoparticles to form heterostructure. When the CNTs content is 10[Formula: see text]wt.%, the Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 nanocomposite exhibits the highest specific capacity of 210[Formula: see text]mAh[Formula: see text]g[Formula: see text] in KOH aqueous electrolytes at current density of 1[Formula: see text]A[Formula: see text]g[Formula: see text]. The superior performances of the Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 nanocomposite are attributed to the effective synergic effects of the high specific capacity of Ni[Formula: see text]Co[Formula: see text]S4 and the excellent conductivity of CNTs. An asymmetric supercapacitor (ASC) was assembled based on Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 positive electrode and activated carbon (AC) negative electrode, which delivers a high energy density of 61.2[Formula: see text]Wh[Formula: see text]kg[Formula: see text] at a power density of 800[Formula: see text]W[Formula: see text]kg[Formula: see text], and maintains 34.8[Formula: see text]Wh[Formula: see text]kg[Formula: see text] at a power density of 16079[Formula: see text]W[Formula: see text]kg[Formula: see text]. Also, the ASC device shows an excellent cycling stability with 91.49% capacity retention and above 94% Columbic efficiency after 10 000 cycles at 10[Formula: see text]A[Formula: see text]g[Formula: see text]. This aqueous asymmetric Ni[Formula: see text]Co[Formula: see text]S4@CNTs//AC supercapacitor is promising for practical applications due to its advantages such as high energy density, power delivery and cycling stability.


2016 ◽  
Vol 45 (22) ◽  
pp. 9103-9112 ◽  
Author(s):  
Sanjit Sarkar ◽  
Sandipan Maiti ◽  
Sourindra Mahanty ◽  
Durga Basak

ZnO/ZnS@Co3O4 pseudocapacitor with high specific capacitance and energy density.


Author(s):  
Jun Song ◽  
Lijun Du ◽  
Jingyi Wang ◽  
Huaiping Zhang ◽  
Yaodong Zhang ◽  
...  

The NiS nanosheets were fabricated using one-step microwave approach with the microwave radiation of 800 W for 1.5 min. Impressively, the NiS nanosheets revealed praiseworthy electrochemical performance, with a capacitance value of 1082.8 F ⋅ g[Formula: see text] at 1 A ⋅ g[Formula: see text] and 77.8% retention over 5000 cycles at 5 A ⋅ g[Formula: see text]. Moreover, an asymmetric supercapacitor was assembled with NiS as the positive electrode and activated carbon (AC) as the negative electrode. It shows 80.42% capacity retention after 8000 cycles and an energy density of 19.45 W ⋅ h ⋅ kg[Formula: see text] at a power density of 801.05 W ⋅ kg[Formula: see text].


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