Electrochemical performance of CNTs/RGO/MnO₂ composite material for supercapacitor

Abstract

In this article, the novel carbon materials (carbon nanotubes (CNTs) and graphene) with high-specific area and superior mechanical behavior are employed to strengthen the specific capacitance and cyclical stability of manganese dioxide (MnO 2) for supercapacitors. The electrode material, synthesized by the CNTs, reduced graphene oxide (RGO), and MnO 2 (CNTs-RGO-MnO 2 composite), is characterized by scanning electron microscope, transmission electron microscope, and X-ray powder diffraction. The results indicate that the MnO 2 particles are compactly distributed on the surface of the RGO and CNTs. The state of MnO 2 in the CNTs/RGO/MnO 2 composite is d-MnO 2. The electrochemical test results indicate that the specific electric capacities of the CNTs/RGO/MnO 2 composite are 404 F/g, 255 F/g, and 82 F/g, respectively, at 1 A/g, 3 A/g, and 10 A/g ampere densities, which illustrate that the addition of the CNTs and RGO greatly hoists the specific capacitance of the MnO 2. Moreover, the long-time charge-discharge test results indicate that the specific capacitance of the CNTs/RGO/MnO 2 composite remains 70% after 5000 circles under the big current density of 30 A/g. The electrochemical impedance spectroscopy test results show that the RGO and CNTs can remarkably reduce the electric charge shifting resistance; at the same time, the electrolyte resistance and electric charge shifting resistance after the charge-discharge test are scarcely increasing, showing that the CNTs/RGO/ MnO 2 composite is a kind of supercapacitor electrode material with stable structure, which has the prospect of industrialization.

Enhanced Supercapacitor Performance and Electromagnetic Interference Shielding Effectiveness of CuS Quantum Dots Grown on Reduced Graphene Oxide Sheets

“…These findings clearly established the successful incorporation of CuS nanoparticles into the RGO sheet . It is anticipated that the observed increase in the crystallinity could also account for the observed improvement in electrochemical performance and EMI shielding property of CuS/RGO nanocomposites. , XRD patterns of RGCS12 and RGCS17 also showed the presence of an additional intense peak at ∼21° in all probability due to the formation of residual intercalation compounds in the RGO sheet …”

Effect of Composition Ratios on the Performance of Graphene/Carbon Nanotube/Manganese Oxide Composites toward Supercapacitor Applications

“…Considering the charge–discharge mechanism, supercapacitors can be classified into three major categories: electrochemical double-layer capacitors (EDLCs), pseudocapacitors, and hybrid capacitors. ,− In general, carbon-based materials such as activated carbon, carbon nanotubes (CNTs), graphene, mesoporous carbon, and carbon-fiber-based materials are frequently employed as the electrode material in EDLCs. ,,,− Each of these has its specific advantages and disadvantages. Among them, multiwall CNTs and single-layered graphene have attracted most research attention because of the corresponding long-term conductivity and high specific surface area (SSA), respectively. , However, in practice, the contact resistance is huge between CNT–CNT, CNT–graphene, and graphene–graphene owing to the large interface between the polymer binder and the nanoparticles.…”

“…Among them, multiwall CNTs and single-layered graphene have attracted most research attention because of the corresponding long-term conductivity and high specific surface area (SSA), respectively. , However, in practice, the contact resistance is huge between CNT–CNT, CNT–graphene, and graphene–graphene owing to the large interface between the polymer binder and the nanoparticles. Moreover, CNT and graphene-based electrodes also suffer from winding into a group and piling up in stacks, respectively. ,,, Integrating them together mitigates those problem to a certain extent. ,,,,, …”

Unveiling high specific energy supercapacitor from layer-by-layer assembled polypyrrole/graphene oxide|polypyrrole/manganese oxide electrode material

“…As shown in Fig. 7b , GCD curves of LBL assembled composite displays asymmetrical triangular shapes from the highest (7.0 A/g) to the lowest (3.0 A/g) current density which indicates the material has good charge-discharge reversibility 30 . However, the discharging time decreases with the increase of current density due to the incapability of the electrolyte ions to enter into the inner structure of the active material and only the outer active surface is utilized for ion diffusion at high current densities 16 , 31 .…”