A review of electrolyte materials and compositions for electrochemical supercapacitors

Zhong, Cheng; Deng, Yida; Hu, Wenbin; Qiao, Jinli; Zhang, Lei; Zhang, Jiujun

doi:10.1039/c5cs00303b

Cited by 2,990 publications

(1,972 citation statements)

References 507 publications

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“…The improved electrochemical properties in KOH can be ascribed to the smaller hydrated ionic radius of K + (3.31 Å), which is lower than the hydrated ionic radius of the Na + (3.58 Å) and Li + (3.82 Å). The ionic conductivity of hydrated ions increases with a decrease in ion size [47]. This facilitated access to the innermost pores of OPAC-1 for the K + and reduced the transition time between the adsorption and desorption processes.…”

Section: Resultsmentioning

confidence: 95%

“…The presence of micropores provides a larger surface for the adsorption-desorption process of electrolyte ions. Mesopores also ensure a highly accessible surface area and offer wider channels for several electrolyte ions to diffuse at the same time without experiencing geometric resistance [14,47]. Therefore, we presumed superior electrochemical performance in OPAC-1 due to the higher fraction of mesopores and enhanced surface area.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Orange-Peel-Derived Carbon: Designing Sustainable and High-Performance Supercapacitor Electrodes

Ranaweera

Kahol

Ghimire

et al. 2017

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Abstract:Interconnected hollow-structured carbon was successfully prepared from a readily available bio-waste precursor (orange peel) by pyrolysis and chemical activation (using KOH), and demonstrated its potential as a high-performing electrode material for energy storage. The surface area and pore size of carbon were controlled by varying the precursor carbon to KOH mass ratio. The specific surface area significantly increased with the increasing amount of KOH, reaching a specific surface area of 2521 m 2 /g for a 1:3 mass ratio of precursor carbon/KOH. However, a 1:1 mass ratio of precursor carbon/KOH displayed the optimum charge storage capacitance of 407 F/g, owing to the ideal combination of micro-and mesopores and a higher degree of graphitization. The capacitive performance varied with the electrolyte employed. The orange-peel-derived electrode in KOH electrolyte displayed the maximum capacitance and optimum rate capability. The orange-peel-derived electrode maintained above 100% capacitance retention during 5000 cyclic tests and identical charge storage over different bending status. The fabricated supercapacitor device delivered high energy density (100.4 µWh/cm 2 ) and power density (6.87 mW/cm 2 ), along with improved performance at elevated temperatures. Our study demonstrates that bio-waste can be easily converted into a high-performance and efficient energy storage device by employing a carefully architected electrode-electrolyte system.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Orange-Peel-Derived Carbon: Designing Sustainable and High-Performance Supercapacitor Electrodes

Ranaweera

Kahol

Ghimire

et al. 2017

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“…Since the ionic conductivity of the ions decreases with increasing size, K + ions provide the highest ionic conductivity and thus can get access to most of the pores within same time frame which results in higher charge storage capacity. [37] The current observed in the CV curves can be described using the power law behavior as given below [38] i av b =…”

Section: Resultsmentioning

confidence: 99%

Eco‐Friendly and High Performance Supercapacitors for Elevated Temperature Applications Using Recycled Tea Leaves

et al. 2017

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energy supply are required. Hence, an efficient local energy storage/production system plays a vital role for such applications. [1] The supercapacitor is one of the efficient energy storage systems which can store energy via electric double layer and faradic reactions. [2,3] The electric double layer capacitor (EDLC) stores the charge over the active surface area of the material and shows very durable performance over long period. [3,4] Thus, creating carbon with a high surface area could be one of the ways to improve the performance of EDLC-based supercapacitor devices. There are several publications documenting the utilization of waste-derived carbon source such as seeds, seed shells, leaves, bagasse, waste paper, and tyre. [5][6][7][8][9][10][11][12] Waste tea is an additional exciting source for carbon. [13] Most of the time, an activation step is required to achieve the high surface area to enhance the performance of the carbon. Activation of waste-derived carbon can be done using various methods including chemical, steam, and CO 2 -based activation. [14][15][16][17] For example, steam activated carbon from fir wood showed an activated surface area of 1131 m 2 g −1 while, CO 2 activated empty fruit bunches of palm showed a surface area of 1704 m 2 g −1 . [12,13] KOH activation is the most popular way to create high surface area and Used tea leaves are utilized for preparation of carbon with high surface area and electrochemical properties. Surface area and pore size of tea leaves derived carbon are controlled by varying the amount of KOH as activating agent. The maximum surface area of 2532 m 2 g −1 is observed, which is much higher than unactivated tea leaves (3.6 m 2 g −1 ). It is observed that the size of the electrolyte ions has a profound effect on the energy storage capacity. The maximum specific capacitance of 292 F g −1 is observed in 3 m KOH electrolyte with outstanding cyclic stability, while the lowest specific capacitance of 246 F g −1 is obtained in 3 m LiOH electrolyte at 2 mV s −1 . The tea leaves derived electrode shows almost 100% capacitance retention up to 5000 cycles of study. The symmetrical supercapacitor device shows a maximum specific capacitance of 0.64 F cm −2 at 1 mA cm −2 and about 95% of specific capacitance is retained after increasing current density to 12 mA cm −2 , confirming the high rate stability of the device. An improvement over 35% in the charge storage capacity is seen when increasing device temperature from 10 to 80 °C. The study suggests that used tea leaves can be used for the fabrication of environment friendly high performance supercapacitor devices at a low cost.

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“…These commonly used redox-active additives for pseudocapacitive or asymmetric supercapacitors are K 3 Fe(CN) 6 , [97] KI, [98] PPD, [99] and HQ. [100] Single redox-active additive may produce high pseudocapacitive at either positive or negative electrodes. For example, an iodine-based system offered high pseudocapacitance on the positive electrode while VOSO 4 can greatly improve the performance of negative electrode.…”

Section: Redox-active Gpes For Supercapacitorsmentioning

confidence: 99%

Gel Polymer Electrolytes for Electrochemical Energy Storage

Cheng

Pan

Zhao

et al. 2017

Advanced Energy Materials

755

562

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storage devices with adjustable shapes and high flexibility, which is promising for the burgeoning portable and wearable electronics. [7][8][9] Furthermore, the flexibility and elasticity of GPEs are also prone to tolerate the volume change of electrode materials and the dendrites of lithium metal during charge and discharge processes. [10][11][12][13] As a consequence, GPEs have become one of the most desirable alternatives among various electrolytes for the electrochemical energy storage devices, and significant progress has been made in lithium-ion batteries (LIBs), supercapacitors (SCs), lithium-oxygen (Li-O 2 ) batteries as well as the other kinds of electrochemical energy storage devices, such as sodium-ion batteries, lithium-sulfur batteries, fuel cells, and zinc-air batteries. [14][15][16] In order to meet the requirements of wearable devices for flexibility and deformability, more special GPEs with tough, [17] stretchable, [18] and compressible [19] functionalities have been also developed.Typically, a polymeric framework is adopted in GPEs as host material, providing high mechanical integrity. Several criteria for a good polymer host lie in: [20][21][22] (i) fast segmental motion of polymer chain; (ii) special groups promoting the dissolution of salts; (iii) low glass transition temperature (T g ); (iv) high molecular weight; (v) wide electrochemical window; (vi) high degradation temperature. Within the framework, the salts in the GPEs serve as the sources of the charge carriers, which are generally required to have large anions and low dissociation energy for easier dissociating-induced free/mobile ions. According to the types of electrolytes, there are four categories of GPEs based on proton, [23] alkaline, [24] conducting salts, and ionic liquids (ILs). [25] The criteria for an appropriate electrolyte include: [26][27][28] (i) good dissociation without forming ion pairs or ion aggregation; (ii) high thermal, chemical, and electrochemical stability; (iii) high ionic conductivity. In order to dissolve both the polymer hosts and electrolytic salts, the organic/ aqueous solvents are introduced to provide the medium for ionic conduction. A good solvent should simultaneously have high dielectric constant (ɛ > 15), donor number for more dissociation of ion and chemical and electrochemical stability. Organic solvents normally include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dimethyl formamide (DMF), dimethyl sulphoxide, ethyl methyl carbonate, and tetrahydrofuran.To prepare a high-performance GPE, it is essential to select the species of host polymer, solvent, and electrolytic salt, and then blend them by solution or melt processes, such as casting With the booming development of flexible and wearable electronics, their safety issues and operation stabilities have attracted worldwide attentions. Compared with traditional liquid electrolytes, gel polymer electrolytes (GPEs) are preferred due to their higher safety and adaptability to the design of ...

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A review of electrolyte materials and compositions for electrochemical supercapacitors

Cited by 2,990 publications

References 507 publications

Orange-Peel-Derived Carbon: Designing Sustainable and High-Performance Supercapacitor Electrodes

Orange-Peel-Derived Carbon: Designing Sustainable and High-Performance Supercapacitor Electrodes

Eco‐Friendly and High Performance Supercapacitors for Elevated Temperature Applications Using Recycled Tea Leaves

Gel Polymer Electrolytes for Electrochemical Energy Storage

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