Nanowindow-Regulated Specific Capacitance of Supercapacitor Electrodes of Single-Wall Carbon Nanohorns

Yang, Cheol‐Min; Kim, Yong-Jung; Endo, Morinobu; Kanoh, Hirofumi; Yudasaka, Masako; Iijima, Sumio; Kaneko, Katsumi

doi:10.1021/ja065501k

Cited by 306 publications

(192 citation statements)

References 16 publications

Supporting

Mentioning

184

Contrasting

Unclassified

Order By: Relevance

“…The latter was varied by changing the macropore radius R 0 from 50 to 150 nm while other geometric parameters such as the carbon wall thickness and mesopore radius respectively remained 2 and 7 nm and identical to those of CP204-S15 mesoporous carbon. 166 The numerical results were obtained using either the solvated or the non-solvated effective ion diameters reported in the literature as a = 1.40 nm 159,160 or a = 0.68 nm, 158 respectively. It is evident that the predicted and experimentally measured gravimetric capacitances C g increased linearly with increasing specific surface area.…”

Section: Equilibrium Modelingmentioning

confidence: 99%

Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors

Pilon

Wang

d’Entremont

2015

J. Electrochem. Soc.

114

105

View full text Add to dashboard Cite

This paper reviews recent advances in physical modeling of interfacial and transport phenomena in electric double layer capacitors (EDLCs) under both equilibrium and dynamic cycling. The models are based on continuum theory and account for (i) the Stern layer at the electrode/electrolyte interface, (ii) finite ion sizes, (iii) steric repulsions, (iv) asymmetric electrolytes featuring ions with different valencies, effective diameters, or diffusion coefficients, (v) electric-field-dependent dielectric permittivity of the electrolyte, and/or (vi) porous three-dimensional morphology of the electrodes. Typical characterization methods such as electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic cycling were reproduced numerically to identify the dominant physical phenomena and to gain insight into experimental observations. In addition, recent thermal models derived from first principles for EDLCs under constant-current cycling accounting for irreversible Joule heating and reversible heat generation rates due to ion diffusion, steric effects, and changes in entropy are discussed. Scaling analyses of both equilibrium and dynamic models are also presented as a way to identify self-similar and asymptotic behaviors as well as to develop design rules for electrodes and electrolytes of next generation EDLCs. Electrical double layer capacitors (EDLCs) store energy by ion adsorption in the electrical double layer (EDL) forming at the electrode/electrolyte interfaces.1,2 This process is highly reversible and the cycle life of EDLCs exceeds 100,000 cycles.2,3 EDLCs can operate in a wide range of specific energy and power densities. This versatility is a key feature for electrical energy storage, energy harvesting, and energy regeneration applications. 2The performance of EDLCs is determined by the combination of the electrode material and morphology and of the electrolyte. In general, the key attributes of a good electrode include 1,3-7 (i) large surface area accessible to ions to maximize charge storage, (ii) optimum pore size, short pore length, and good pore connectivity to facilitate ion transport, (iii) large electrical conductivity to enable fast charging and discharging and low ohmic resistance, (iv) thin electrodes and current collectors to reduce the total resistance of the device, (v) small leakage current, (vi) small self-discharge, (vii) environmentally friendly materials, and (viii) low price. However, satisfying all these criteria simultaneously is challenging. For example, increasing surface area often results in larger electrode electrical resistivity.1 Micropores with diameter less than 2 nm contribute greatly to EDLCs capacitance.2 But pores smaller than the ion size are typically inactive and do not contribute to charge storage. 1,8 Porous electrodes must also be electrochemically accessible to ions. Then, interconnected mesopores with diameter ranging from 2 to 50 nm are necessary for fast charging thanks to their easier accessibility to ions. 1,6,[9][10][11] In practice, electrode...

show abstract

Section: Equilibrium Modelingmentioning

confidence: 99%

Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors

Pilon

Wang

d’Entremont

2015

J. Electrochem. Soc.

114

105

View full text Add to dashboard Cite

show abstract

“…At negative polarizations, when the carbon pore size is decreased below 1 nm ͑900°C sample͒, pores start to become too narrow to efficiently accommodate the cations ͓1.30 and 0.67 nm with ͑Et 4 N + ·7AN͒ and without the solvation shell, respectively 13,23 ͔. For pores equal to or smaller than 0.76 nm ͑700°C sample͒, the capacitive behavior is poor, with a huge resistive part linked to the cationtransport limitation in the pores due to a size effect.…”

Section: Bfmentioning

confidence: 99%

Microelectrode Study of Pore Size, Ion Size, and Solvent Effects on the Charge/Discharge Behavior of Microporous Carbons for Electrical Double-Layer Capacitors

Lin

Taberna

Chmiola

et al. 2009

J. Electrochem. Soc.

243

162

View full text Add to dashboard Cite

The capacitive behavior of TiC-derived carbon powders in two different electrolytes, NEt 4 BF 4 in acetonitrile ͑AN͒ and NEt 4 BF 4 in propylene carbonate ͑PC͒, was studied using the cavity microelectrode ͑CME͒ technique. Comparisons of the cyclic voltammograms recorded at 10-1000 mV/s enabled correlation between adsorbed ion sizes and pore sizes, which is important for understanding the electrochemical capacitive behavior of carbon electrodes for electrical double-layer capacitor applications. The CME technique also allows a fast selection of carbon electrodes with matching pore sizes ͑different sizes are needed for the negative and positive electrodes͒ for the respective electrolyte system. Comparison of electrochemical capacitive behavior of the same salt, NEt 4 BF 4 , in different solvents, PC and AN, has shown that different pore sizes are required for different solvents, because only partial desolvation of ions occurs during the double-layer charging. Squeezing partially solvated ions into subnanometer pores, which are close to the desolvated ion size, may lead to distortion of the shape of cyclic voltammograms. Global warming, as well as the increasing price and decreasing availability of fossil fuels, all highlight the need to move toward a sustainable development where renewable energy and electric/ hybrid vehicle engines are widely used. Renewable energy sources such as sunlight, wind, or hydro ͑rivers, waves, etc.͒ generate electrical energy which must be stored for use in autonomous systems such as transportation or electronics. Therefore, the development of high-performance electrical-energy storage devices is required.There are two major types of electrical-energy storage devices, batteries and electrical double-layer capacitors ͑EDLCs͒. Batteries are electrochemical-energy storage devices that can be fully discharged in a few minutes or hours efficiently. Li-ion batteries, for example, exhibit high specific energy ͑ϳ150 Wh/kg͒ but are today limited in high-power delivery/uptake as well as in low-temperature operation ͑failure below −20°C͒ and cycle life.1 EDLCs, also known as supercapacitors or ultracapacitors, can be reversibly charged/discharged at higher rates as compared to batteries, thus enabling energy recovery ͑harvesting͒ at much higher rates as well.2,3 Their cycle life ͑Ͼ500,000 cycles͒ as well as lowtemperature operation ͑down to −40°C͒ positively compare to batteries. However, the specific energy of supercapacitors is about 20 times less than that of Li-ion batteries. EDLCs thus have to be used complementary with batteries in many of the applications where high-power delivery/uptake is needed, such as in hybrid electric vehicles, photo and video cameras, cell phones, etc. 3Recent publications suggested that a real breakthrough in improving the specific energy of EDLCs could be obtained using tailored microporous carbons 4 such as carbide-derived carbons ͑CDCs͒.5 CDCs are obtained by the extraction of a metal from its carbide at high temperatures.6-8 Using TiC as the precursor and chlo...

show abstract

“…For this reason, carbon has become the material of choice for many commercial supercapacitors. Among the types of carbon that have been studied in detail are activated carbon (the industry standard) [6][7][8][9][10][11][12][13], various templated carbons [14][15][16][17][18][19][20][21][22][23], carbon black [24][25][26][27], carbon aerogel [28][29][30][31][32], carbon nanotubes [33][34][35][36][37][38][39][40][41][42][43][44][45][46], and graphene [47][48][49][50][51][52][53][54][55]…”

Section: Introductionmentioning

confidence: 99%

A universal equivalent circuit for carbon-based supercapacitors

Fletcher

Black

Kirkpatrick

2013

J Solid State Electrochem

130

View full text Add to dashboard Cite

A universal equivalent circuit is proposed for carbon-based supercapacitors. The circuit, which actually applies to all porous electrodes having non-branching pores, consists of a single vertical ladder network in series with an RC parallel network. This elegant arrangement explains the three most important shortcomings of present-day supercapacitors, namely open circuit voltage decay, capacitance loss at high frequency, and voltammetric distortion at high scan rate. It also explains the shape of the complex plane impedance plots of commercial devices and reveals why the equivalent series capacitance increases with temperature. Finally, the construction of a solid-state supercapacitor simulator is described. This device is based on a truncated version of the universal equivalent circuit, and it allows experimenters to explore the responses of different supercapacitor designs without having to modify real supercapacitors.

show abstract

Nanowindow-Regulated Specific Capacitance of Supercapacitor Electrodes of Single-Wall Carbon Nanohorns

Cited by 306 publications

References 16 publications

Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors

Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors

Microelectrode Study of Pore Size, Ion Size, and Solvent Effects on the Charge/Discharge Behavior of Microporous Carbons for Electrical Double-Layer Capacitors

A universal equivalent circuit for carbon-based supercapacitors

Contact Info

Product

Resources

About