Three dimensional manganese oxide on carbon nanotube hydrogels for asymmetric supercapacitors

Cheng, Hanlin; Duong, Hai M.; Jewell, Daniel

doi:10.1039/c6ra02858f

Cited by 26 publications

(8 citation statements)

References 49 publications

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“…The weight ratio of MnO 2 /RGO (77.0:23.0 wt %) was close to that of 5-MnO 2 /IL-G. As expected, MnO 2 and MnO 2 /RGO compared with MnO 2 /IL-G showed much lower specific capacitances of 264 F/g for MnO 2 and 325 F/g for MnO 2 /RGO at 25 mV/s and severely inferior rate capabilities of 19.3 and 38.5% retentions for MnO and MnO 2 /RGO at 1000 mV/s (Figure S11). Notably, the specific capacitance of 507 F/g obtained at a high rate of 1000 mV/s for 5-MnO 2 /IL-G was still much higher than those of other previously reported metal oxide/carbon electrodes obtained even at lower rates, including MnO 2 /carbon aerogel (124 F/g at 5 mV/s), 3D-MnO 2 /CNT (182 F/g at 2 mV/s), MnO 2 /RGO-activated carbon (123 F/g at 10 mV/s), MnO 2 /RGO (23 F/g at 5 mV/s), TiO 2 /graphene (250 F/g at 2 A/g), VO X /carbon (191 F/g at 0.5 mV/s), ZrO 2 /GO (299 F/g at 1 mV/s), Co 3 O 4 /activated carbon (491 F/g at 0.5 A/g), and Fe 3 O 4 /activated carbon (150 F/g at 3 A/g) electrodes. The long-term stability of the electrode was further tested by applying sequential current densities of 1 and 10 A/g over 20 000 cycles.…”

Section: Resultscontrasting

confidence: 53%

Fast and Scalable Hydrodynamic Synthesis of MnO₂/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

Hong

Jeong

Kang

et al. 2018

ACS Appl. Mater. Interfaces

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The integration of metal oxides and carbon materials provides a great potential for enhancing the high energy and power densities of supercapacitors, but the rational design and scalable fabrication of such composite materials still remain a challenge. Herein, we report a fast, scalable, and one-pot hydrodynamic synthesis for preparing ion conductive and defect-free graphene from graphite and MnO 2 /graphene nanocomposites. The use of this hydrodynamic method using Taylor−Couette flow allows us to efficiently fast shear-exfoliate graphite into large quantities of high-quality graphene sheets. Deposition of MnO 2 on graphene is subsequently performed in a fluidic reactor within 10 min. The prepared MnO 2 /graphene nanocomposite shows outstanding electrochemical performances, such as a high specific capacitance of 679 F/g at 25 mV/s, a high rate capability of 74.7% retention at an extremely high rate of 1000 mV/s, and an excellent cycling characteristic (∼94.7% retention over 20 000 cycles). An asymmetric supercapacitor device is fabricated by assembling an anode of graphene and a cathode of MnO 2 / graphene, which resulted in high energy (35.2 W h/kg) and power (7.4 kW/kg) densities (accounting for the mass of both electrodes and the electrolyte) with a high rate capability and long cycle life.

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Section: Resultscontrasting

confidence: 53%

Fast and Scalable Hydrodynamic Synthesis of MnO₂/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

Hong

Jeong

Kang

et al. 2018

ACS Appl. Mater. Interfaces

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“…The ASCs showed an energy density of 33.3 Wh kg –1 at a power density of 7.8 kW kg –1 , which still delivered a energy density of 31.0 Wh kg –1 at a higher power density of 14.8 kW kg –1 . Notably, the energy density of as-assembled ASCs was comparable and even higher than those of other reported ASCs, including 3D graphene//MnO 2 /Ni foam (14.9 Wh kg –1 ), graphene//MnO 2 /graphene (30.4 Wh kg –1 ), AC//MnO 2 (17 Wh kg –1 ), AC//Mn 3 O 4 /CNT (26.6 Wh kg –1 ), AC//MnO 2 /carbon fiber (24.8 Wh kg –1 ), and carbon//MnO 2 /carbon (15.3 Wh kg –1 ) . The excellent electrochemical performance of as-assembled ASCs (3D HC//3D MnO 2 /HC) should be attributed to low ohmic loss, accelerated electron/ion transfer, and superior structural integrity of MnO 2 wires during charging/discharging process.…”

Section: Resultsmentioning

confidence: 66%

MnO₂ Nanowire/Biomass-Derived Carbon from Hemp Stem for High-Performance Supercapacitors

et al. 2017

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Hierarchical 3D nanostructures based on waste biomass are being offered as promising materials for energy storage due to their processabilities, multifunctionalities, environmental benignities, and low cost. Here we report a facile, inexpensive, and scalable strategy for the fabrication of hierarchical porous 3D structure as electrode materials for supercapacitors based on MnO nanowires and hemp-derived activated carbon (HC). Vertical MnO wires are uniformly deposited onto the surface of HC using a one-step hydrothermal method to produce hierarchical porous structures with conductive interconnected 3D networks. HC acts as a near-ideal 3D current collector and anchors electroactive materials, and this confers a specific capacitance of 340 F g at 1 A g with a high rate capability (88% retention) of the 3D MnO/HC composite because of its open-pore system, which facilitates ion and electron transports and synergistic contribution of two energy-storage materials. Moreover, asymmetric supercapacitors fabricated using 3D HC as the anode and 3D MnO/HC as the cathode are able to store 33.3 Wh kg of energy and have a power delivery of 14.8 kW kg.

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“…Conversely, the highest-areal capacitance materials made by VACNT-Mn 3 O 4 (1.5 F/cm 2 ) take advantage of the unique vertically aligned morphology but have exhibited relatively low specific mass capacitance (125 F/g) due to insufficient and nonuniform loading of active MnO x materials via wet chemical approaches. In the materials presented here, the intrinsically aligned, interconnected porous structure and directed 1D electron transport via VACNTs, coupled with the unique ALD coating method, enable the preservation of both high specific gravimetric and areal capacitance; i.e., the co-optimization of the specific areal and mass specific capacitance performance demonstrated here is greater than that of any other reported CNT-MnO x hybrid materials (Figure includes both CDI-related − and supercapacitor-related materials ,− ,,− ).…”

Section: Resultsmentioning

confidence: 85%

High-Performance Capacitive Deionization via Manganese Oxide-Coated, Vertically Aligned Carbon Nanotubes

Shi

Zhou

et al. 2018

Environ. Sci. Technol. Lett.

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Discovering electrode materials with exceptional capacitance, an indicator of the ability of a material to hold charge, is critical for developing capacitive deionization devices for water desalination. Maganese oxides (MnO x ) have shown promise as capacitive electrode materials, but they exhibit a trade-off in which a higher loading of the active MnO x comes at the cost of lower conductivity. To address this challenge and achieve high salt adsorption, we fabricated electrodes comprising vertically aligned core–shell nanostructures using atomic layer deposition (ALD) to coat thin films of MnO x onto vertically aligned carbon nanotubes (VACNTs). The inherently hierarchical, anisotropic, three-dimensional macroporous structure of VACNTs and the tunable coating, a hallmark of ALD, enabled co-optimization of the hybrid material’s specific capacitance with respect to mass and geometric area. The specific capacitance was optimized in this study to 215 ± 7 F/g and 1.1 ± 0.1 F/cm2 in a 1 M NaCl electrolyte at a scan rate of 5 mV/s. This material exhibited a remarkable sodium ion adsorption capacity of 490 ± 30 μmol of Na/g of material (2-fold higher than that of pristine VACNTs) at a functioning voltage of 1.2 V, which may ultimately enable expanded desalination applications of capacitive deionization.

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Three dimensional manganese oxide on carbon nanotube hydrogels for asymmetric supercapacitors

Abstract: Three dimensional manganese oxide on a CNT hydrogel has been developed with a satisfactory electrochemical performance.

Cited by 26 publications

References 49 publications

Fast and Scalable Hydrodynamic Synthesis of MnO₂/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

Fast and Scalable Hydrodynamic Synthesis of MnO₂/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

MnO₂ Nanowire/Biomass-Derived Carbon from Hemp Stem for High-Performance Supercapacitors

High-Performance Capacitive Deionization via Manganese Oxide-Coated, Vertically Aligned Carbon Nanotubes

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Three dimensional manganese oxide on carbon nanotube hydrogels for asymmetric supercapacitors

Abstract: Three dimensional manganese oxide on a CNT hydrogel has been developed with a satisfactory electrochemical performance.

Cited by 26 publications

References 49 publications

Fast and Scalable Hydrodynamic Synthesis of MnO2/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

Fast and Scalable Hydrodynamic Synthesis of MnO2/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

MnO2 Nanowire/Biomass-Derived Carbon from Hemp Stem for High-Performance Supercapacitors

High-Performance Capacitive Deionization via Manganese Oxide-Coated, Vertically Aligned Carbon Nanotubes

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Fast and Scalable Hydrodynamic Synthesis of MnO₂/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

Fast and Scalable Hydrodynamic Synthesis of MnO₂/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life

MnO₂ Nanowire/Biomass-Derived Carbon from Hemp Stem for High-Performance Supercapacitors