Microwave-assisted hydrothermal synthesis of crystalline WO3–WO3·0.5H2O mixtures for pseudocapacitors of the asymmetric type

Chang, Kuo‐Hsin; Hu, Chi-Chang; Huang, Chao-Ming; Liu, Yaling; Chang, Chia-Wei

doi:10.1016/j.jpowsour.2010.09.078

Cited by 135 publications

(55 citation statements)

References 28 publications

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“…This enhancement results from the additive effect of fast superficial redox reactions and electric double layer formation at the electrode/electrolyte interface. [12,[16][17][18][19][20][21][22][23] show promising pseudocapacitive behaviour as well as reasonable capacity retention in asymmetric systems in the negative potential region.…”

Section: Introductionmentioning

confidence: 99%

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

Upadhyay

Altomare

Eugénio

et al. 2017

Electrochimica Acta

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Keywords: electrochemical anodization WO 3 nanostructure phosphoric acid supercapacitor energy storage A B S T R A C T Herein we illustrate the functionality as pseudocapacitive material of tungsten trioxide (WO 3 ) nanochannel layers fabricated by electrochemical anodization of W metal in pure hot ortho-phosphoric acid (o-H 3 PO 4 ). These layers are characterized by a defined nanochannel morphology and show remarkable pseudocapacitive behaviour in the negative potential (À0.8-0.5 V) in neutral aqueous electrolyte (1 M Na 2 SO 4 ). The maximum volumetric capacitance of 397 F cm À3 is obtained at 2 A cm À3. The WO 3 nanochannel layers display full capacitance retention (up to 114%) after 3500 charge-discharge cycles performed at 10 A cm À3 . The relatively high capacitance and retention ability are attributed to the high surface area provided by the regular and defined nanochannel morphology. Kinetic analysis of the electrochemical results for the best performing WO 3 structures, i.e., grown by 2 h-long anodization, reveals the occurrence of pseudocapacitance and diffusional controlled processes. Electrochemical impedance spectroscopy measurements show for the same structures a relatively low electrical resistance, which is the plausible cause for the superior electrochemical behaviour compared to the other structures.

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Section: Introductionmentioning

confidence: 99%

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

Upadhyay

Altomare

Eugénio

et al. 2017

Electrochimica Acta

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show abstract

“…The capacitive behaviors of the nanostructured tungsten oxides have been also investigated as supercapacitor electrodes [23][24][25][26][27][28][29]. However, the low electrical conductivity and poor rate performance of tungsten oxide pseudocapacitors have been their major demerits.…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal preparation and supercapacitive performance of flower-like WO3·H2O/reduced graphene oxide composite

Zhou

et al. 2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Although studies on the asymmetric systems and applicability of non-aqueous electrolytes to oxide electrodes in order to widen the operating voltage window have recently been initiated, non-aqueous electrolytes have yet to surpass aqueous electrolytes in terms of specific capacitance. [3][4][5][6][7][8] Electrolytes near neutral pH are selected for materials that are not as corrosion-resistant in acids and base, for example manganese oxide.9-12 Neutral electrolytes are more environmentally benign and its low corrosiveness allows a wider range in choice for periphery material, such as current collectors and packaging.13 Despite the RuO 2 -based material being the model pseudocapacitive material, studies on the electrochemical capacitor behavior in neutral electrolytes are scarce compared to the more popular acidic or basic electrolytes. One of the reasons is that the capacitance of RuO 2 in neutral electrolytes is generally 1/2 of that in sulfuric acid or potassium hydroxide.…”

mentioning

confidence: 99%

Towards Implantable Bio-Supercapacitors: Pseudocapacitance of Ruthenium Oxide Nanoparticles and Nanosheets in Acids, Buffered Solutions, and Bioelectrolytes

Makino

Ban

Sugimoto

2015

J. Electrochem. Soc.

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Metal oxides, in particular ruthenium-based oxides, are promising electrode materials for aqueous pseudocapacitors. Strong acids or bases are favored over neutral electrolytes owing to the higher capacitance. Here we explore the pseudocapacitive behavior of ruthenium oxide nanoparticles and nanosheets in near neutral pH as an environmentally benign electrolyte. The pseudocapacitive charge storage in poorly-crystalline hydrous RuO 2 nanoparticles, and highly-crystalline RuO 2 nanosheets were investigated in acetic acid-lithium acetate (AcOH-AcOLi) buffered solutions. It is shown that capacitance values as high as 1,038 F g −1 can be achieved in AcOH-AcOLi buffered solutions with RuO 2 nanosheets, which is 44% higher than the benchmark RuO 2 · nH 2 O in H 2 SO 4 electrolyte (720 F g −1 ). Furthermore, comparable performance was obtained in phosphate buffered saline and fetal bovine serum. The mechanism of the pseudocapacitive properties is discussed based on the difference in the surface redox behavior of different RuO 2 nanomaterials in acid, neutral, buffered solutions, and in weak acid. Electrochemical capacitors (also known as supercapacitors) are energy harvesting devices capable of charge and discharging within a few seconds, and cycle life in the order of thousands of cycles. Some metal-oxides are known to provide high capacitance in aqueous electrolytes, owing to the combination of the non-faradaic electrical double layer charging and the faradaic surface or near surface confined redox capacitance (psuedocapacitance).1 Pseudocapacitance is a phenomenon generally observed in aqueous electrolytes.2 Acidic or basic electrolytes such as H 2 SO 4 and KOH are favorable in terms of power density owing to the high conductivity. RuO 2 is one of the rare oxides that is stable in both acidic and basic conditions. Hydrous RuO 2 nanoparticles (RuO 2 · nH 2 O; where n is typically 0.5) offers capacitance of ∼700 F g −1 in H 2 SO 4 electrolyte and can be cycled for thousands of cycles with practically no decay, thus is often used for performance benchmarking of new electrode materials. Although studies on the asymmetric systems and applicability of non-aqueous electrolytes to oxide electrodes in order to widen the operating voltage window have recently been initiated, non-aqueous electrolytes have yet to surpass aqueous electrolytes in terms of specific capacitance. [3][4][5][6][7][8] Electrolytes near neutral pH are selected for materials that are not as corrosion-resistant in acids and base, for example manganese oxide.9-12 Neutral electrolytes are more environmentally benign and its low corrosiveness allows a wider range in choice for periphery material, such as current collectors and packaging.13 Despite the RuO 2 -based material being the model pseudocapacitive material, studies on the electrochemical capacitor behavior in neutral electrolytes are scarce compared to the more popular acidic or basic electrolytes. One of the reasons is that the capacitance of RuO 2 in neutral electrolytes is generally 1/2 of that in s...

show abstract

Microwave-assisted hydrothermal synthesis of crystalline WO3–WO3·0.5H2O mixtures for pseudocapacitors of the asymmetric type

Cited by 135 publications

References 28 publications

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

Hydrothermal preparation and supercapacitive performance of flower-like WO3·H2O/reduced graphene oxide composite

Towards Implantable Bio-Supercapacitors: Pseudocapacitance of Ruthenium Oxide Nanoparticles and Nanosheets in Acids, Buffered Solutions, and Bioelectrolytes

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