共查询到20条相似文献,搜索用时 31 毫秒
1.
Xiaoxiao Yang Kang Fu Linchang Mao Junhong Jin Shenglin Yang Guang Li 《Ceramics International》2019,45(1):759-766
Three-dimensional (3D) flower-like Co2(OH)3Cl-MnO2 nanostructures were fabricated inside eggshell through a facile and effective method. Inspired by semipermeable membranes, a shell membrane was selected as an interface for ion diffusion. In specific, an eggshell with shell membrane was employed as a multifunctional reactor to separate the components of the precursor solution. OH- ion diffusion was performed through porous eggshell membrane. The electrochemical measurements demonstrated that the hybrid composite achieves high capacitance 3.709?F/cm2 at 1?mA/cm2 (2061?F/g with the mass loading of 1.8?mg/cm2) and an excellent cycling stability (71% specific capacitance retained after 5000 cycle numbers), exhibiting a superior electrochemical performance compared to pure Co2(OH)3Cl or MnO2. Moreover, an asymmetric supercapacitor was assembled by Co2(OH)3Cl-MnO2-2 and activated carbon as positive and negative electrode, respectively (Co2(OH)3Cl-MnO2-2//AC ASC), which exhibits high capacitance (134.8?F/g at 0.2?A/g), excellent energy density (42.2?W?h/kg at 150.3?W/kg), and remarkable cycling stability (80% capacitance retention after consecutive 5000 cycle numbers). 相似文献
2.
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
3.
Shengde Dong Yuan Zhou Chunxi Hai Jinbo Zeng Yanxia Sun Yue Shen Xiang Li Xiufeng Ren Guicai Qi Xinxing Zhang Luxiang Ma 《Ceramics International》2019,45(1):144-152
In this study, we have successfully coated the CeO2 nanoparticles (CeONPs) layer onto the surface of the Ni-rich layered LiNi0.7Co0.2Mn0.1O2 cathode materials by a wet chemical method, which can effectively improve the structural stability of electrode. The X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) are used to determine the structure, morphology, elemental composition and electronic state of pristine and surface modified LiNi0.7Co0.2Mn0.1O2. The electrochemical testing indicates that the 0.3?mol% CeO2-coated LiNi0.7Co0.2Mn0.1O2 demonstrates excellent cycling capability and rate performance, the discharge specific capacity is 161.7?mA?h?g?1 with the capacity retention of 86.42% after 100 cycles at a current rate of 0.5?C, compared to 135.7?mA?h?g?1 and 70.64% for bare LiNi0.7Co0.2Mn0.1O2, respectively. Even at 5?C, the discharge specific capacity is still up to 137.1?mA?h?g?1 with the capacity retention of 69.0%, while the NCM only delivers 95.5?mA?h?g?1 with the capacity retention of 46.6%. The outstanding electrochemical performance is assigned to the excellent oxidation capacity of CeO2 which can oxidize Ni2+ to Ni3+ and Mn3+ to Mn4+ with the result that suppress the occurrence of Li+/Ni2+ mixing and phase transmission. Furthermore, CeO2 coating layer can protect the structure to avoid the occurrence of side reaction. The CeO2-coated composite with enhanced structural stability, cycling capability and rate performance is a promising cathode material candidate for lithium-ion battery. 相似文献
4.
Hyung-Wook Ha 《Electrochimica acta》2006,51(16):3297-3302
CeO2-coated LiCoO2 particles were successfully synthesized by a sol-gel coating of CeO2 on the surface of the LiCoO2 powder and subsequent heat treatment at 700 °C for 5 h. The surface-modified and pristine LiCoO2 powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), slow rate cyclic voltammogram (CV), and differential scanning calorimetry (DSC). Cyclic voltammetry curves suggested that the CeO2 coating suppressed the phase transitions. Unlike pristine LiCoO2, the CeO2-coated LiCoO2 cathode exhibited better capacity retention than the pristine LiCoO2 electrode in the higher cutoff voltage. Differential scanning calorimetric data revealed the higher thermal stability of the CeO2-coated LiCoO2 electrode. 相似文献
5.
Hidayat Ullah Shah Fengping Wang Muhammad Sufyan Javed Nusrat Shaheen Muhammad Saleem Yan Li 《Ceramics International》2018,44(4):3580-3584
Mn3O4 nanoparticles (NPs) are decorated with reduced graphene oxide nanosheets (rGO-Mn3O4) through a facile and eco-friendly hydrothermal method. The as-synthesized composite was characterized by XRD, SEM, TEM and Raman spectroscopy. The electrochemical properties of (rGO-Mn3O4) nanocomposite were studied as electrode materials for supercapacitors. The rGO-Mn3O4 nanocomposite exhibit high specific capacitance of 457 Fg?1 at 1.0 A/g in 1 M Na2SO4 aqueous electrolyte. The rGO-Mn3O4 exhibits good capacitance retention by achieving 91.6% of its initial capacitance after 5000 cycles. The excellent electrochemical performance is attributed to the increased electrode conductivity in the presence of graphene network. 相似文献
6.
A series of cerium dioxide (CeO2)/polyimide (PI) nanocomposites were successfully prepared from Ce(Phen)3 and polyamic acid (PAA) via the solution direct-dispersing method, followed by a step thermal imidization process. TGA and XPS studies showed that the cerium complex decomposed to form CeO2 during the thermal imidization process at 300 °C. SEM observation showed that the formed CeO2 as nanoparticles was well dispersed in polyimide matrix with a size of about 50-100 nm for samples with different contents of CeO2. Thermal analysis indicated that the introduction of CeO2 decreased the thermal stability of nanocomposite films due to the decomposition of Ce(Phen)3 in the imidization process, while the glass transition temperature (Tg) increased obviously, especially nanocomposite films with high loading of CeO2 exhibited a trend of disappearance of Tg. DMTA and static tensile measurements showed that the storage modulus of nanocomposite films increased, while the elongation at break decreased with increasing CeO2 content. 相似文献
7.
Graphene-based materials are promising electrodes for supercapacitors, owing to their unique two-dimensional structure, high surface area, remarkable chemical stability, and electrical conductivity. In this paper, graphene is explored as a platform for energy storage devices by decorating graphenes with flower-like MnO2 nanostructures fabricated by electrodeposition. The as-prepared graphene and MnO2, which were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), have been assembled into an asymmetric supercapacitor. The specific capacitance of the graphene electrode reached 245 F/g at a charging current of 1 mA after an electro-activation process. This value is more than 60% larger than the one before electro-activation. The MnO2 nano-flowers which consisted of tiny rods with a thickness of less than 10 nm were coated onto the graphene electrodes by electrodeposition. The specific capacitance after the MnO2 deposition is 328 F/g at the charging current of 1 mA with an energy density of 11.4 Wh/kg and 25.8 kW/kg of power density. This work suggests that our graphene-based electrodes are a promising candidate for the high-performance energy storage devices. 相似文献
8.
X.M. Liu 《Electrochimica acta》2004,49(2):229-232
NiO/RuO2 composite materials were prepared for use in electrochemical capacitors (ECs) by co-precipitation method followed by heat treatment. X-ray diffraction (XRD) spectra indicated that no new structural materials were formed and ruthenium oxide particles were coated by NiO particles. RuO2 partly introduced into NiO-based electrode had improved its electrochemical performance and capacitive properties by using electrochemical measurements. A maximum specific capacitance of 210 F/g was obtained for NiO-based composite electrode with 10 wt.% RuO2 in the voltage range from −0.4 to 0.5 V in 1 mol/l KOH solution. By comparison of effect of modified modes on the specific capacitance, chemically modified composite electrodes had more stable cycling properties than those of physically modified electrodes. After 200 cycles, specific capacitance of NiO-based chemical composite electrode with 5 wt.% RuO2 kept 95% above, while that of physical electrode was only 79% of initial specific capacitance. 相似文献
9.
MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy
analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture
is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements.
The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast
electron and ion transport. 相似文献
10.
Gomaa A.M. Ali Mashitah M. Yusoff H. Algarni Kwok Feng Chong 《Ceramics International》2018,44(7):7799-7807
We present a facile one-step electrochemical approach to generate MnO2/rGO nanocomposite from a mixture of Mn3O4 and graphene oxide (GO). The electrochemical conversion of Mn3O4 into MnO2 through potential cycling is expedited in the presence of GO while the GO is reduced into reduced graphene oxide (rGO). The MnO2 nanoparticles are evenly distributed on the rGO nanosheets and act as the spacer to prevent rGO nanosheets from restacking. This unique structure provides high electroactive surface area (1173?m2 g?1) that improves ions diffusion within the MnO2/rGO structure. As a result, the MnO2/rGO nanocomposite exhibits high specific capacitance of 473?F?g?1 at 0.25?A?g?1, which is remarkably higher (3 times) than the Mn3O4/GO prior conversion. In addition, the electrosynthesized nanocomposite shows higher conductivity and excellent potential cycling stability of 95% at 2000 cycles. 相似文献
11.
Changzhou Yuan Linrui Hou Diankai Li Chuangang Fan Xiaogang Zhang 《Electrochimica acta》2010,56(1):115-121
A loose whisker-like Co(OH)2 was synthesized by means of polyethylene glycol 4000 as soft template under ultrasonic condition, and investigated as an active electrode material for electrochemical capacitors. The composition and microstructure of the as-prepared Co(OH)2 were investigated by X-ray diffraction spectroscopy and transmission electron microscopy. The formation mechanism of the whisker-like Co(OH)2 was attentively proposed based on Fourier transform infrared spectroscopy analysis. Electrochemical studies revealed that the whisker-like Co(OH)2 delivered a specific capacitance of 325 F/g at a current density of 20 mA/cm2 (ca. 1.3 A/g) and even 279 F/g at 80 mA/cm2 (ca. 5.3 A/g) due to its special nanostructure, indicating its fast electrochemical response property. A capacitance attenuation of ca. 7% over 1000 cycles meant the good cyclic stability of the whisker-like Co(OH)2 for electrochemical capacitors application. 相似文献
12.
Balasubramaniam Saravanakumar Tae Hoon Ko Byoung-Suhk Kim 《Ceramics International》2018,44(9):10635-10645
The development of hierarchical, porous film based current collector has created huge interest in the area of energy storage, sensor, and electrocatalysis due to its higher surface area, good electrical conductivity and increased electrode-electrolyte interface. Here, we report a novel method to prepare a hierarchically ramified nanostructured porous thin film as a current collector by dynamic hydrogen bubble template electro-deposition method. At a first time, we report a porous 3D-Ni decorated with ZnCo2O4 and Fe2O3 by simple, low-cost electrochemical deposition method. The fabricated porous 3D-Ni based electrodes showed an excellent electrochemical property such as high specific capacitance, excellent rate capability, and good cycle stability. The asymmetric solid-state supercapacitor device was fabricated using porous, 3D Ni decorated with ZnCo2O4 and Fe2O3 as the positive and negative electrodes. The fabricated ZnCo2O4//Fe2O3 asymmetric device delivered an areal capacitance of 92?mF?cm?2 at a current density of 0.5?mA?cm?2 with a maximum areal power density of 3?W?cm?2 and areal energy density of 28.8?mWh?cm?2. The higher performances of porous, 3D current collector have a huge potential in the development of high performance supercapacitor. 相似文献
13.
Poly 3,4-ethylenedioxythiophene (PEDOT)-based NiFe2O4 conducting nanocomposites were synthesized and their electrochemical properties were studied in order to find out their suitability as electrode materials for supercapacitor. Nanocrystalline nickel ferrites (5-20 nm) have been synthesized by sol-gel method. Reverse microemulsion polymerization in n-hexane medium for PEDOT nanotube and aqueous miceller dispersion polymerization for bulk PEDOT formation using different surfactants have been adopted. Structural morphology and characterization were studied using XRD, SEM, TEM and IR spectroscopy. Electrochemical performances of these electrode materials were carried out using cyclic voltammetry at different scan rates (2-20 mV/s) and galvanostatic charge-discharge at different constant current densities (0.5-10 mA/cm2) in acetonitrile solvent containing 1 M LiClO4 electrolyte. Nanocomposite electrode material shows high specific capacitance (251 F/g) in comparison to its constituents viz NiFe2O4 (127 F/g) and PEDOT (156 F/g) where morphology of the pore structure plays a significant role over the total surface area. Contribution of pseudocapacitance (CFS) arising from the redox reactions over the electrical double layer capacitance (CDL) in the composite materials have also been investigated through the measurement of AC impedance in the frequency range 10 kHz-10 mHz with a potential amplitude of 5 mV. The small attenuation (∼16%) in capacitance of PEDOT-NiFe2O4 composite over 500 continuous charging/discharging cycles suggests its excellent electrochemical stability. 相似文献
14.
Graphene, graphene-ZnO and graphene-SnO2 films were successfully synthesized and used as electrode materials for electrochemical supercapacitors, respectively. The screen-printing approach was employed to fabricate graphene film on graphite substrate while the ZnO and SnO2 were deposited on graphene films by ultrasonic spray pyrolysis. The electrochemical performances of these electrodes were comparatively analyzed through electrochemical impedance spectrometry, cyclic voltammetry and chronopotentiometry tests. The results showed that the incorporation of ZnO or SnO2 improved the capacitive performance of graphene electrode. Graphene-ZnO composite electrode exhibited higher capacitance value (61.7 F/g) and maximum power density (4.8 kW/kg) as compared with graphene-SnO2 and pure graphene electrodes. 相似文献
15.
Improvement of electrochemical stability of LiMn2O4 by CeO2 coating for lithium-ion batteries 总被引:1,自引:0,他引:1
Hyung-Wook Ha 《Electrochimica acta》2007,52(9):3236-3241
CeO2-coated LiMn2O4 spinel cathode was synthesized using two-step synthesis method. All the samples exhibited a pure cubic spinel structure without any impurities in the XRD patterns. The results of the electrochemical performances on CeO2-coated electrode are compared to those of electrodes based on LiMn2O4 spinel without CeO2 coating. CeO2-coated LiMn2O4 cathode improved the cycling stability of the electrode. The capacity retention of 2 wt% CeO2-coated LiMn2O4 was more than 82% after 150 cycles between 3.0 and 4.4 V at room temperature and 82% after 40 cycles at elevated temperature of 60 °C. The amounts of dissolved manganese-ions in CeO2-coated LiMn2O4 significantly are smaller than pristine LiMn2O4 systems especially at elevated temperatures. Surface-modified LiMn2O4 can suppress the dissolution reaction of manganese-ions at elevated temperature and clearly improve the cyclability of the spinel LiMn2O4 cathode materials. 相似文献
16.
In this paper, a cerium dioxide (CeO2) modified titanium dioxide (TiO2) nanotube array film was fabricated by electrodeposition of CeO2 nanoparticles onto an anodized TiO2 nanotube array. The structural investigation by X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that the CeO2 nanoparticles grew uniformly on the walls of the TiO2 nanotubes. The composite was composed of cubic-phase CeO2 crystallites and anatase-phase TiO2 after annealing at 450 °C. The cyclic voltammetry and chronoamperometric charge/discharge measurement results indicated that the CeO2 modification obviously increased the charge storage capacity of the TiO2 nanotubes. The charge transfer process at the surface, that is, the pseudocapacitance, was the dominate mechanism of the charge storage in CeO2-modified TiO2 nanotubes. The greater number of surface active sites resulting from uniform application of the CeO2 nanoparticles to the well-aligned TiO2 nanotubes contributed to the enhancement of the charge storage density. 相似文献
17.
Mn3O4 nanoparticles have been homogenously deposited within highly dense, millimeter-long carbon nanotube array (CNTA) by dip-casting method from non-aqueous solutions. After modified with Mn3O4 nanoparticles, CNTAs have been changed from hydrophobic to hydrophilic without their alignment and integrity being destroyed. The hydrophilic Mn3O4/CNTA composite electrodes present improved performance for supercapacitors, compared with as-grown CNTA electrodes. The maximum specific capacitance of the Mn3O4/CNTA composite electrode was found to be 143 F/g, leading to an exceptionally high area-normalized capacitance (Faraday per geometric area of the electrode) of 1.70 F/cm2, while the specific capacitance for as-grown CNTA electrode is only 1–2 F/g. When normalized to the deposited Mn3O4 nanoparticles, the specific capacitance was estimated to be as high as 292 F/g. The method is promising for producing high performance area-limited electrochemical supercapacitors and provides a new route of decorating highly dense CNTAs with active materials. 相似文献
18.
In the zinc hydrometallurgy process, the key to reduce the voltage of the corrosion is to reduce the oxygen evolution potential of the anode. In this experiment, the effects of doped CeO2 and graphite powder (GP) on the electrochemical properties of Ti/PbO2 were investigated. Ti/PbO2, Ti/PbO2-CeO2, Ti/PbO2-GP and Ti/PbO2-CeO2-GP anode were prepared by direct current (DC) plating. The surface morphology and composition of these different Ti/PbO2 electrodes before and after polarisation were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion mechanism was analysed by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The cell voltage, current efficiency, service life and failure mechanism of Ti/PbO2 anodes were observed and analysed by simulating electrowinning experiments. The results show that Ti/PbO2-CeO2-GP anodes is denser than other electrodes. Ti/PbO2-CeO2 (12?g/L)-GP (8?g/L) with the lowest anode potential is 1.5390?V. The potential of the lowest oxygen evolution peak of the Ti/PbO2-CeO2 (12?g/L)-GP (8?g/L) electrode is 0.824?V. The Ti/PbO2-CeO2-GP anode had a minimum cell voltage of 2.85?V and a current efficiency of 95.8%. The Ti/PbO2-CeO2-GP has a minimum corrosion rate of ??0.0320?g·A?1·h?1 and a longest anode lifetime of up to 127?h. The best electrode for the surface coating is Ti/PbO2-CeO2 (12?g/L)-GP (8?g/L). 相似文献
19.
Pure and SiO2-supported CeO2 samples were prepared by Ce(NO3)3 decomposition, precipitation, and sol–gel methods in an attempt to study the role of SiO2 in the synthesis of these materials. During synthesis process, SiO2 support uniformly adsorbed cerium ions in aqueous solution, preventing nucleation and crystal growth of CeO2 during the subsequent water evaporation and calcination steps. Uniform adsorption and inhibition were enhanced by NH4+ and, to a larger extent, C5H7O5COO-. Despite the dispersion of cerium ions on SiO2 reduced the temperature at which CeO2 was formed, crystal size and crystallinity of CeO2 in composites were significantly lower than that of pure CeO2 sample prepared by the same synthesis method and at the same temperature. Composites were quite stable upon increasing the temperature from 400 to 800?°C. Visible light absorption, reduction, and photocatalytic activity characteristics of CeO2 were improved upon dispersion on SiO2. This work can help synthetize supported oxides with high activity and thermal stability. 相似文献
20.
Transparent and adherent CeO2-ZrO2 thin films having film thicknesses ∼543-598 nm were spray deposited onto the conducting (fluorine doped tin oxide coated glass) substrates from a blend of equimolar concentrations of cerium nitrate hexahydrate and zirconium nitrate having different volumetric proportions (0-6 vol.% of Zr) in methanol. CeO2-ZrO2 films were polycrystalline with cubic fluorite crystal structure and the crystallinity was improved with increasing ZrO2 content. Films were highly transparent (T ∼ 92%), showing decrease in band gap energy from 3.45 eV for pristine CeO2 to 3.08-3.14 eV for CeO2-ZrO2 films. The different morphological features of the film obtained at various CeO2-ZrO2 compositions had pronounced effect on the ion storage capacity and electrochemical stability. CeO2-ZrO2 film prepared at 5 vol.% Zr concentration exhibited higher ion storage capacity of 24 mC cm−2 and electrochemical stability of 10,000 cycles in 0.5 M LiClO4 + PC electrolyte due to its film thickness (584 nm) coupled with relatively larger porosity (8%). The optically passive behavior of such CeO2-ZrO2 film (with 5 vol.% Zr) is affirmed by its negligible transmission modulation irrespective of repeated Li+ and electron insertion/extraction. The coloration efficiency of spray deposited WO3 thin film is found to enhance from 47 to 107 cm2 C−1 when CeO2-ZrO2 is coupled as a counter electrode with WO3 in an electrochromic device (ECD). These films can be used as stable ‘passive’ counter electrodes in electrochromic smart windows as they retain full transparency in both the oxidized and reduced states and ever-reported longevity. 相似文献