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1.
Although supercapacitors have higher power density than batteries, they are still limited by low energy density and low capacity retention. Here we report a high-performance supercapacitor electrode of manganese oxide/reduced graphene oxide nanocomposite coated on flexible carbon fiber paper (MnO2–rGO/CFP). MnO2–rGO nanocomposite was produced using a colloidal mixing of rGO nanosheets and 1.8 ± 0.2 nm MnO2 nanoparticles. MnO2–rGO nanocomposite was coated on CFP using a spray-coating technique. MnO2–rGO/CFP exhibited ultrahigh specific capacitance and stability. The specific capacitance of MnO2–rGO/CFP determined by a galvanostatic charge–discharge method at 0.1 A g−1 is about 393 F g−1, which is 1.6-, 2.2-, 2.5-, and 7.4-fold higher than those of MnO2–GO/CFP, MnO2/CFP, rGO/CFP, and GO/CFP, respectively. The capacity retention of MnO2–rGO/CFP is over 98.5% of the original capacitance after 2000 cycles. This electrode has comparatively 6%, 11%, 13%, and 18% higher stability than MnO2–GO/CFP, MnO2/CFP, rGO/CFP, and GO/CFP, respectively. It is believed that the ultrahigh performance of MnO2–rGO/CFP is possibly due to high conductivity of rGO, high active surface area of tiny MnO2, and high porosity between each MnO2–rGO nanosheet coated on porous CFP. An as-fabricated all-solid-state prototype MnO2–rGO/CFP supercapacitor (2 × 14 cm) can spin up a 3 V motor for about 6 min.  相似文献   

2.
Supercapacitors are promising for high power application in the recent years. In particular, the conversion of simple and available carbon materials into economic and high performance electrical devices receives excellent scientific and technological interest. This paper reports a one-step strategy for synthesizing hierarchical porous carbon derived from phenolic resin (PR), which is then used to configure electric double-layer capacitors (EDLCs). Here, a carbon material with a flexible porous structure, large specific surface area, and high graphitization degree is prepared using potassium ferrate (K2FeO4) to catalytically activate PR and to realize synchronous carbonization and graphitization. This method overcomes the disadvantage of time-consuming, high-cost, and environmentally unfriendly. In addition, the as-prepared carbon material has a high specific surface area (1086 m2 g?1) and a large pore size (3.07 nm), which can increase the transfer rate of electrolyte ions. The specific capacitance of the obtained electrode material is 315 F g?1 at 1.0 A g?1, and the optimized electrode material has an ultra-long cycle lifetime (capacitance retention rate is 96.3% after 10,000 cycles). Thus, the hierarchically Fe-doped porous carbon material derived from PR material is expected to realize high rate capacitance for supercapacitor applications.  相似文献   

3.
《Ceramics International》2017,43(7):5374-5381
The MnO2 nanoflowers/reduced graphene oxide composite is coated on a nickel foam substrate (denoted as MnO2 NF/RGO @ Ni foam) via the layer by layer (LBL) self-assembly technology without any polymer additive, following the soft chemical reduction. The layered MnO2 NF/RGO composite is uniformly anchored on the Ni foam skeleton to form the 3D porous framework, and the interlayers have access to lots of ions channels to improve the electron transfer and diffusion. This special construction of 3D porous structure is beneficial to the enhancement of electrochemical property. The specific capacitance is up to 246 F g−1 under the current density of 0.5 A g−1. After 1000 cycles, it can retain about 93%, exhibiting excellent cycle stability. The electrochemical impedance spectroscopy measurements confirm that MnO2 NF/RGO @ Ni foam electrode has lower RESR and RCT values when compared to MnO2 @ Ni foam and RGO @ Ni foam. This study opens a new door to the preparation of composite electrodes for high performance supercapacitor.  相似文献   

4.
MnO2 embedded PPy nanocomposite (MnO2/PPy) thin film electrodes were electrochemically synthesized over polished graphite susbtrates. Growing PPy polymer chains provides large surface area template that enables MnO2 to form as nanoparticles embeded within polymer matrix. Co-deposition of MnO2 and PPy has a complimentary action in which porous PPy matrix provides high active surface area for the MnO2 nanoparticles and, on the other hand, MnO2 nanoparticles nucleated over polymer chains contribute to enhanced conductivity and stability of the nanocomposite material by interlinking the PPy polymer chains. The MnO2/PPy nanocomposite thin film electrodes show significant improvement in the redox performance as cyclic voltammetric studies have shown. Specific capacitance of the nanocomposite is remarkably high (∼620 F g−1) in comparision to its constituents MnO2 (∼225 F g−1) and PPy (∼250 F g−1). Photoelectron spectroscopy studies show that hydrated manganese oxide in the nanocomposite exists in the mixed Mn(II) to Mn(IV) oxidation states. Accordingly, chemical structures of MnO2 and PPy constituents in the nanocomposite are not influenced by the co-deposition process. The MnO2/PPy nanocomposite electrode material however shows significantly improved high specific capacitity, charge-discharge stability and the redox performance properties suitable for application in the high energy density supercapcitors.  相似文献   

5.
《Ceramics International》2020,46(8):11874-11881
As shining stars of 2-dimensional materials, transition metal carbides (MXene) and transition metal oxides have attracted much interest in various energy fields due to their excellent conductive and electrochemical properties. However, big challenge still remains in the accessibility of high-performance fibrous electrodes for flexible supercapacitors. In this paper, MnO2 nanorods are loaded on MXene sheets to obtain MnO2@MXene composites by a facile hydrothermal method, which are subsequently coated on carbon nanotube fibers (CNTFs). With a fine control on morphology, the resulting MnO2@MXene/CNTF electrode exhibits a high specific capacitance of 181.8 F/g at 1 A/g, a capacitance retention of 91% after 5000 charge-discharge cycles, as well as superb flexibility, i.e., neglected capacitance loss at a bending angle of 180°. The as-fabricated flexible composite fiber opens a new door for transition metal carbides and transition metal oxides with great potential in flexible electronics.  相似文献   

6.
MWCNT-PSS/PEDOT/MnO2 nano-composite electrodes were fabricated by generating pseudo-capacitive poly(3,4-ethylenedioxythiophene) (PEDOT)/MnO2 nano-structures on poly(styrene sulfonate) (PSS) dispersed multiwalled carbon nanotubes (MWCNTs). PSS dispersed MWCNTs (MWCNT-PSS) facilitated the growth of PEDOT and MnO2 into nano-rods with large active surface area and good electrical conductivity. The ternary MWCNT-PSS/PEDOT/MnO2 nano-composite electrode was studied for the application in super-capacitors, and exhibited excellent capacitive behavior between −0.2 V and 0.8 V (vs. saturated Ag/AgCl electrode) with high reversibility. Specific capacitance of the nano-composite electrode was found as high as 375 F g−1. In contrast, specific capacitance of MWCNT-PSS/MnO2 and MWCNT-PSS nano-composite electrodes is 175 F g−1 and 15 F g−1, respectively. Based on cyclic voltammetric studies and cycle-life tests, the MWCNT-PSS/PEDOT/MnO2 nano-composite electrode gave a highly stable and reversible performance up to 2000 cycles. Our studies demonstrate that the synergistic combination of MWCNT-PSS, PEDOT and MnO2 has advantages over the sum of the individual components.  相似文献   

7.
The composites of polypyrrole/manganese dioxide/polypropylene fibrous films (PPy/MnO2/PPF) have been prepared in situ through chemical oxidation polymerization by using the mixture of FeCl3·6H2O and MnO2 adsorbed on PPF as oxidant in the atmosphere of pyrrole vapor at room temperature. The morphologies and structures of the composites are investigated by using scanning electron microscope and X-ray diffraction spectroscopy. The properties of the capacitor cells assembled by the composites of PPy/MnO2/PPF are evaluated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy methods. The results reveal that the morphologies, conductivities and capacitance performance of the composites are influenced strongly by the content of MnO2 in the solution of oxidant. The capacitors assembled by PPy/MnO2/PPF exhibit the property of quick charge/discharge, and the highest specific capacitance of about 110 F g−1 is obtained when the PPy/MnO2 content in the composite is about 17.4%.  相似文献   

8.
Core-shell hierarchical structured composites have demonstrated great advantages in numerous energy storage devices. In particular, structured composites with rationally structural components and controllable morphology are the most effective in enhancing electrochemical properties. In this work, MnO2@NiCo2O4@Ti3SiC2/CC (carbon cloth) core-shell hierarchical structured composites were designed and successfully synthesized via electrospinning followed by a two-step hydrothermal reaction. The Ti3SiC2/CC nanofibers and core-shell nanoarrays were able to improve the specific capacitance and cycling stability. In the three-electrode system, the specific capacitance of MnO2@NiCo2O4@Ti3SiC2/CC was observed as 1938.2 F/g at a current density of 1 A/g, while the rate capability retention was observed as 81.7% between 1 and 10 A/g. Furthermore, a superior cycling stability was observed following 5000 cycles with a specific capacitance retention rate of 55.4%. Employing MnO2@NiCo2O4@Ti3SiC2/CC as the all solid-state supercapacitor positive electrode exhibited a high energy density of 58.0 W h/kg at the power density of 800 W/kg. Results demonstrate the potential of the MnO2@NiCo2O4@Ti3SiC2/CC as an electrode material with phenomenal electrochemical properties for supercapacitors.  相似文献   

9.
《Ceramics International》2022,48(11):15721-15728
Developing a new strategy to effectively prevent the restacking of MXene nanosheets will have significant impacts on designing flexible supercapacitor electrodes. Herein, a novel Ti3C2Tx/polyvinyl alcohol (PVA) porous sponge with 3D interconnected structures is prepared by sol-gel and freeze-dried methods. This Ti3C2Tx/PVA porous sponge is used as the template of in-situ polyaniline (PANI) polymerization, and the fabricated PANI@Ti3C2Tx/PVA hydrogel composite is applied as flexible supercapacitors electrodes. 1D conductive polymer chains PVA could increase the interlayer spacing of Ti3C2Tx nanosheets, which is beneficial to expose more electrochemical active sites. The supercapacitor based on PANI@Ti3C2Tx/PVA hydrogel composite exhibits the coexistence of double-layer capacitance and pseudocapacitance behavior. This supercapacitor shows a maximum areal specific capacitance of 103.8 mF cm?2 at 2 A m?2, and it also exhibits a maximum energy density of 9.2 μWh·cm?2 and an optimum power density of 800 μW cm?2. The capacitance of this supercapacitor is almost not change under different bending angles. Moreover, 99% capacitance retention is achieved after 10 000 charge/discharge cycles of the supercapacitor. The synergistic effect between PANI and Ti3C2Tx/PVA composite may improve the number of reactive sites and provide efficient channels for ion diffusion/electron transport.  相似文献   

10.
Carbon nanofibers (CNFs)/MnO2 nanocomposites were prepared as freestanding electrodes using in situ redox deposition and electrospinning. The electrospun CNFs substrates with porosity and interconnectivity enabled the uniform incorporation of birnessite-type MnO2 deposits on each fiber, thus showing unique and conformal coaxial nanostructure. CNFs not only provided considerable specific surface area for high mass loading of MnO2 but also offered reliable electrical conductivity to ensure the full utilization of MnO2 coatings. The effect of MnO2 loading on the electrochemical performances was investigated by cyclic voltammetry (CV), impedance measurements and Galvonostatic charging/discharging technique. The results showed that an ultrathin MnO2 deposits were indispensable to achieve better electrochemical performance. The maximum specific capacitance (based on pristine MnO2) attained to 557 F/g at a current density of 1 A/g in 0.1 M Na2SO4 electrolyte when the mass loading reached 0.33 mg/cm2. This freestanding electrode also exhibited good rate capability (power density of 13.5 kW/kg and energy density of 20.9 Wh/kg at 30 A/g) and long-term cycling stability (retaining 94% of its initial capacitance after 1500 cycles). These characteristics suggested that such freestanding CNFs/MnO2 nanocomposites are promising for high-performance supercapacitors.  相似文献   

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