Hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam for aqueous asymmetric supercapacitors

Xu, Kaibing; Li, Wenyao; Liu, Qian; Li, Bo; Liu, Xijian; An, Li; Chen, Zhigang; Zou, Rujia; Hu, Junqing

doi:10.1039/c3ta14647b

Cited by 356 publications

(153 citation statements)

References 68 publications

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“…(b) Relatively less positive potentials (0.4e1 V) are preferred under potentiostatic mode, as at which electron transfer rather than mass transfer controlled nucleation and growth occurs [61,90,93,121]. (c) Under galvanostatic mode, small deposition current densities (0.2e1 mA cm À2 ) are chosen to assure a low overpotential and slow growth rate for uniform deposition [75,129,131,135]. (d) Pulse deposition technics, including pulse potential [60,93,146] and current [66,182] …”

Section: Anodic Electrodepositionmentioning

confidence: 99%

Materials and fabrication of electrode scaffolds for deposition of MnO2 and their true performance in supercapacitors

Cao

Wang

et al. 2015

Journal of Power Sources

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Section: Anodic Electrodepositionmentioning

confidence: 99%

Materials and fabrication of electrode scaffolds for deposition of MnO2 and their true performance in supercapacitors

Cao

Wang

et al. 2015

Journal of Power Sources

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“…Along such idea, many kinds of nanomaterials, [9][10][11] especially hollow spheres, 12 have been developed to improve pseudocapacitors, but the increased contact resistance often emerges in these porous materials. On the other hand, increasing conductivity will greatly favor the Faradaic reactions, which has been demonstrated typically in the integration of oxides with metal foam, 13 carbon cloth, 9 graphene and carbon nanotubes. 14 However, these methods do not change the intrinsic properties of the metal oxides.…”

Section: Introductionmentioning

confidence: 99%

Integrating large specific surface area and high conductivity in hydrogenated NiCo2O4 double-shell hollow spheres to improve supercapacitors

et al. 2015

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Increasing specific surface area and electrical conductivity are two crucial ways to improve the capacitive performance of electrode materials. Nanostructure usually enlarges the former but reduces the later; thus, it is still a great challenge to overcome such contradiction. Here, we report hydrogenated NiCo 2 O 4 double-shell hollow spheres, combining large specific surface area and high conductivity to improve the capacitive performance of supercapacitors. The specific surface area of NiCo 2 O 4 hollow spheres, fabricated via programmed coating of carbon spheres, was enlarged 50% (from 76.6 to 115.2 m 2 g − 1 ) when their structure was transformed from single-shell to double-shell. Furthermore, activated carbon impedance measurements demonstrated that the low-temperature hydrogenation greatly decreased both the internal resistance and the Warburg impedance. Consequently, a specific capacitance increase of 462%, from 445 to 718 F g − 1 , was achieved at a current density of 1 A g − 1 .Underlying such great improvement, the evolution of chemical valence and defect states with co-increase of these two factors was explored through X-ray photoelectron spectroscopy. Moreover, a full cell combined with NiCo 2 O 4 and AC was assembled, and an energy density of 34.8 Wh kg − 1 was obtained at a power density of 464 W kg − 1 . NPG Asia Materials (2015) 7, e165; doi:10.1038/am.2015.11; published online 13 March 2015 INTRODUCTION Supercapacitors, also known as electrochemical capacitors, have attracted great attention because of their outstanding power density, long cycling life and fast charge/discharge ability. 1-3 These virtues make them remarkable candidates for the electrical sources of hybrid electric vehicles, for which strong explosiveness is highly desired. Principally, supercapacitors run according to ion adsorption (electrochemical double-layer capacitors) or fast Faradaic reactions (pseudocapacitors) mechanisms. Comparatively speaking, the former has low specific capacitance and hence hard to satisfy the growing demand of peak-power assistance in electric vehicles. 4 Thus, more and more attentions were focused on pseudocapacitive electrode materials because their energy density associated with Faradaic reactions is much larger than that of electrochemical double-layer capacitors. [5][6][7][8] To improve performances of pseudocapacitors, two crucial factors are usually considered for the electrode materials, they are large specific surface area and high conductivity for electrolyte ions and electrons. On the one hand, large specific surface area will provide more electroactive sites for the Faradaic reactions, and load more doublelayer charges. Along such idea, many kinds of nanomaterials, 9-11 especially hollow spheres, 12 have been developed to improve

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“…Furthermore, we tested their cycling performance at constant current density of 16 mA cm −2 (Fig.13 c). For the both electrode materials, their specific capacitance increase first and then decrease slightly, and this is due to the activation process of the electrodes at the initial stage of CV cycling test as previously reported [19,37,50]. Before the first 200 cycles, the NiCo2O4 shows better performance than that of NiCo2O4/MnO2.…”

Section: Characterization and Evaluation Of The Nico2o4/mno2 With Thementioning

confidence: 63%

“…This indicates that more MnO2 formed over the surface of NiCo2O4. From the SEM images displayed in [9,19]. With the rise of scan rate, the anodic peaks shifted towards positive potential and the cathodic peaks shifted towards negative potential.…”

Section: Electrochemical Measurementsmentioning

confidence: 96%

“…For example, the A@B structure: NiCo2O4@MnO2 [9,19,20], ZnCo2O4@MnO2 [21], CuCo2O4@MnO2 [22],Co3O4@MnO2 [10,23,24], NiCo2S4@MnO2, [25,26], ZnO2@MnO2 [17], Fe2O3@MnO2 [27], MnO2@MnO2 [28], TiO2@MnO2 [29,30], CuO@MnO2 [31],Co3O4@Au@MnO2 [32], Co3O4@Pt@MnO2 [33], WO3-x@Au@MnO2 [34], MnO2/Mn/MnO2 [35]; the A/B structure: NiCo2O4/MnO2 [36,37], Ni(OH)2/MnO2 [8,13], NiCo2S4/MnO2 [38],…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

NiCo2O4 / MnO2 heterostructured nanosheet: influence of preparation conditions on its electrochemical properties

Deng

Tie

Lan

et al. 2015

Electrochimica Acta

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Hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam for aqueous asymmetric supercapacitors

Cited by 356 publications

References 68 publications

Materials and fabrication of electrode scaffolds for deposition of MnO2 and their true performance in supercapacitors

Materials and fabrication of electrode scaffolds for deposition of MnO2 and their true performance in supercapacitors

Integrating large specific surface area and high conductivity in hydrogenated NiCo2O4 double-shell hollow spheres to improve supercapacitors

NiCo2O4 / MnO2 heterostructured nanosheet: influence of preparation conditions on its electrochemical properties

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