Deposition of MnO 2 nanoneedles on carbon nanotubes and graphene nanosheets as electrode materials for electrochemical capacitors

Hsieh, Chien‐Te; Tzou, Dong-Ying; Lee, Wen-Yen; Hsu, Jo-Pei

doi:10.1016/j.jallcom.2015.11.021

Cited by 24 publications

(8 citation statements)

References 35 publications

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“…Note that the Galvanostatic discharge curves in Figure c show a linear voltage decay rather than plateaus at low potentials. These sloping voltage profiles are considered one of the hallmarks of pseudocapacitive behavior, which can be assigned to a fast adsorption of Li + onto the MnO 2 crystals . Figure S14 of the Supporting Information shows the contributions (in %) from the intercalation process (denoted as α), conversion reaction (denoted as β) and capacitive process (denoted as γ) to the total capacity in different rates.…”

Section: Resultsmentioning

confidence: 91%

Unveiling Conversion Reaction on Intercalation‐Based Transition Metal Oxides for High Power, High Energy Aqueous Lithium Battery

Zhi

Han

et al. 2018

Advanced Energy Materials

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required for the operation of dangerous flammable electrolytes inevitably incur substantial cost, which introduces more difficulties in fabrication of large scale energy storage systems. [5] To tackle these safety and sustainability concerns at their roots, aqueous lithium-ion batteries (ALiBs) were first proposed in 1994, and has since drawn significant attention. [6][7][8] However, due to limited practical capacity of cathode materials based on Li + intercalation mechanism (between 110 and 140 mAh g −1 ) [9,10] and the narrow electrochemical stability window (avoiding hydrogen and oxygen evolution, generally not exceeding 1.2 V), [11,12] the package-level energy density, even in its ceiling value is normally less than 50 Wh kg −1 , which cannot meet the requirements of commercial electrical vehicles, such as Nissan Leaf and Tesla Model S. [13,14] It has been also reported that based on Li + adsorption mechanism on both sides of MnO 2 monolayer, a high theoretical capacity up to 616 mAh g −1 can be obtained. [15] However, this value is only on the basis of first-principles calculations, and more experimental evidence is needed. As a result, breakthroughs in performance of ALiBs are required, which may only come from the development of novel concepts in energy storage mechanism, probably different from intercalation chemistry.Recently, conversion reactions in transition metal oxide structures (e.g., MnO x , CoO x , and CuO x ) with Li + have been reported to show a large, rechargeable capacity in lithium-ion cells of organic electrolytes. [16][17][18] The specific capacity of these materials can be as high as 1000 mAh g −1 (about seven times that of common Li + intercalation materials), [19] which can potentially boost the energy density of lithium-ion batteries. However, in contrast to that of organic electrolyte systems where cathode and anode materials often operate under high conversion potentials, [20] the operating potential window in aqueous electrolyte batteries is far below the thermodynamic voltage limit of cathode and anode materials. [19] Therefore, a conversion reaction between transition metal oxides and alkaline metals (or ions) in ALiBs has been believed impossible. [21,22] In this study, against the conventional belief, we report that a reversible conversion reaction can happen between Li + and semicrystalline MnO 2 (scMO) prepared from a conventional Aqueous lithium batteries are reaching their energy and power limits partly due to limited capacity from intercalation chemistry. Alternatively, conversion reactions bring added capacity that can significantly increase the capacity ceiling of the cell. However, such reactions can only be realized in organic electrolytes, and similar redox chemistry in aqueous lithium batteries is not reported yet. In this work, it is discovered that a large work function difference (up to 1.78 eV) between crystalline LiMn 2 O 4 (cLMO) and semicrystalline MnO 2 (scMO) makes energy bands of MnO 2 bend downward toward their interface, resulting in the accumulation of f...

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Section: Resultsmentioning

confidence: 91%

Unveiling Conversion Reaction on Intercalation‐Based Transition Metal Oxides for High Power, High Energy Aqueous Lithium Battery

Zhi

Han

et al. 2018

Advanced Energy Materials

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“…Self-supported electrode of hollow activated carbon fiber -CNT has been prepared by direct CVD deposition and investigated in 1 mM H2SO4 solution and obtained 240 F/g specific capacitance [16]. CNT on carbon fiber electrodes also used in multicomponent composite films in order to enhance the conductivity, and electrochemical capacitive performance of electrodes, such as electroactive layers in hybrid supercapacitors, such as polyaniline [17][18][19], MnO2 [19,20] or Fe2O3 [21], or enhanced supercapacitor performance of double layer capacitors, such as porous hybrid graphene-carbon nanotube layer on carbon fiber surface [22].…”

Section: Introductionmentioning

confidence: 99%

Properties of electrochemical double-layer capacitors with carbon-nanotubes-on-carbon-fiber-felt electrodes

Felhősi

Keresztes

Marek

et al. 2020

Electrochimica Acta

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Carbon nanotube (CNT) layers deposited on carbon fiber cloth (CFC) materials have been studied as electrodes of electrochemical double layer capacitors (EDLCs), in particular, the electrochemical performance and cycle stability of symmetric EDLCs in an organic electrolyte (tetraethyl-ammonium-fluoroborate in acetonitrile). Due to the large surface area of carbonfibers, the CNT mass loading can be as high as 18 mg/cm 2 which is magnitudes larger than that of what can be deposited on aluminum or nickel metal sheets. The area normalized double layer capacitance of CNT/CFC electrodes in the above organic electrolytes were found to be in the range of 100-400 mF/cm 2 , and the specific capacitances were 18 to 48 F/g. These latter values are below the achievable values of single-wall CNT of 80 F/g; the lower values can be attributed to the presence of multi-walled CNTs of some quantities, having lower accessible surface area. The energy density of CNT/CFC supercapacitors is 0.8-1.5 Wh/kg, while the power density varies between 5-20 kW/kg calculated on electrode level. Excellent cycling stability of EDLCs built with CNT-on carbon felt electrodes has been demonstrated up to 1 million cycles, which is due to the inert nature of substrate causing the absence of corrosion process and high mass load of CNT.

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“…It is well known that the supercapacitive performance of PCMs strongly depends on their nanostructure. Although clear efforts aimed at designing advanced PCMs with well-defined nanostructure for optimizing supercapacitive properties are hot research aspects, e.g., carbon nanospheres [13, 14], carbon nanotubes [15, 16], and carbon nanorods [17, 18], their practical applications are significantly limited by the high cost, multi-step processes, and heavily usage of toxic strong oxidants [19]. …”

Section: Introductionmentioning

confidence: 99%

Activated Carbon Fibers with Hierarchical Nanostructure Derived from Waste Cotton Gloves as High-Performance Electrodes for Supercapacitors

Wei

Yang

et al. 2017

Nanoscale Res Lett

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One of the most challenging issues that restrict the biomass/waste-based nanocarbons in supercapacitor application is the poor structural inheritability during the activating process. Herein, we prepare a class of activated carbon fibers by carefully selecting waste cotton glove (CG) as the precursor, which mainly consists of cellulose fibers that can be transformed to carbon along with good inheritability of their fiber morphology upon activation. As prepared, the CG-based activated carbon fiber (CGACF) demonstrates a surface area of 1435 m2 g−1 contributed by micropores of 1.3 nm and small mesopores of 2.7 nm, while the fiber morphology can be well inherited from the CG with 3D interconnected frameworks created on the fiber surface. This hierarchically porous structure and well-retained fiber-like skeleton can simultaneously minimize the diffusion/transfer resistance of the electrolyte and electron, respectively, and maximize the surface area utilization for charge accumulation. Consequently, CGACF presents a higher specific capacitance of 218 F g−1 and an excellent high-rate performance as compared to commercial activated carbon.

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Deposition of MnO 2 nanoneedles on carbon nanotubes and graphene nanosheets as electrode materials for electrochemical capacitors

Cited by 24 publications

References 35 publications

Unveiling Conversion Reaction on Intercalation‐Based Transition Metal Oxides for High Power, High Energy Aqueous Lithium Battery

Unveiling Conversion Reaction on Intercalation‐Based Transition Metal Oxides for High Power, High Energy Aqueous Lithium Battery

Properties of electrochemical double-layer capacitors with carbon-nanotubes-on-carbon-fiber-felt electrodes

Activated Carbon Fibers with Hierarchical Nanostructure Derived from Waste Cotton Gloves as High-Performance Electrodes for Supercapacitors

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