Cross-Linked Polymer Hydrogel Electrolytes for Electrochemical Capacitors

Choudhury, Nurul A.; Shukla, A. K.; Sampath, S.; Pitchumani, S.

doi:10.1149/1.2164810

Cited by 106 publications

(76 citation statements)

References 45 publications

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“…Ionic conduction in pristine GHE takes place by the Grötthus-type mechanism of proton transport, whereas that in NaCl-doped GHE takes place predominantly by free diffusion of hydrated Na + and Cl − ions. As described earlier, 36 transport of protons in aqueous media by a Grötthus-type mechanism takes place along chains of hydrogenbonded water molecules. In this mechanism, transport of protons take by alternation of covalent and hydrogen bonds with little physical movement of protons.…”

Section: A76mentioning

confidence: 84%

“…The continuity in the long-range network of hydrogen-bonded water molecules might not prevail in the cross-linked GHE as in uncrosslinked or less cross-linked aqueous gelatin solutions. Consequently, proton transport in pristine GHE by a Grötthus-type mechanism 36 will be less effective. The decreased proton mobility resulting from increased glutaraldehyde concentration is responsible for the decreased ionic conductivity in pristine GHE.…”

Section: A76mentioning

confidence: 99%

“…Recently, a study on aqueous PGEs comprised of aqueous PVA/PAA blend hydrogel electrolytes with acidic, alkaline, and neutral dopants has been reported. 36 Hydrogels are three-dimensional polymeric networks with large quantities of water absorbed in the polymer matrices. The threedimensional network formation and its insolubility in the parent solution are due to the presence of chemical cross-links or physical entanglements.…”

mentioning

confidence: 99%

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Gelatin Hydrogel Electrolytes and Their Application to Electrochemical Supercapacitors

Choudhury¹,

Sampath

Shukla

2008

J. Electrochem. Soc.

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Gelatin hydrogel electrolytes ͑GHEs͒ with varying NaCl concentrations have been prepared by cross-linking an aqueous solution of gelatin with aqueous glutaraldehyde and characterized by scanning electron microscopy, differential scanning calorimetry, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic chronopotentiometry. Glass transition temperatures for GHEs range between 339.6 and 376.9 K depending on the dopant concentration. Ionic conductivity behavior of GHEs was studied with varying concentrations of gelatin, glutaraldehyde, and NaCl, and found to vary between 10 −3 and 10 −1 S cm −1 . GHEs have a potential window of about 1 V. Undoped and 0.25 N NaCl-doped GHEs follow Arrhenius equations with activation energy values of 1.94 and 1.88 ϫ 10 −4 eV, respectively. Electrochemical supercapacitors ͑ESs͒ employing these GHEs in conjunction with Black Pearl Carbon electrodes are assembled and studied. Optimal values for capacitance, phase angle, and relaxation time constant of 81 F g −1 , 75°, and 0.03 s are obtained for 3 N NaCl-doped GHE, respectively. ES with pristine GHE exhibits a cycle life of 4.3 h vs 4.7 h for the ES with 3 N NaCl-doped GHE. Polymer electrolytes are widely studied materials with applications in electrochemical devices. Although the ionic conductivity behavior of solid polymer electrolytes, such as polyethylene oxidesalt complexes, was reported as early as in 1973 by Wright, the potential of these materials as a new class of solid electrolytes for energy storage applications was envisaged by Armand in 1978. [1][2][3][4] Solid polymer electrolytes exhibit ionic conductivity between 10 −8 and 10 −7 S cm −1 that is too low to be significant for devices. Accordingly, efforts have been expended to enhance the ionic conductivity of polymer electrolytes.1,2 One such approach involves addition of plasticizer, a low-molecular-weight polar solvent, such as ethylene carbonate, to a polymer-salt system to realize polymer gel electrolyte ͑PGE͒.5-8 These PGEs are solid, have good adhesive properties, and exhibit high ionic conductivity of about 10 −3 S cm −1 at ambient temperatures. Although such nonaqueous PGEs have a wider potential window of about 4 V as compared to about 1 V for their aqueous counterpart, preparation and handling of the former require a moisture-free environment that is both involved and costintensive. Besides, organic solvents used as plasticizers with nonaqueous PGEs are environmentally toxic. 5Electrochemical supercapacitors ͑ESs͒ are electrochemical power systems with highly reversible charge-storage and delivery capabilities. ESs have properties complementary to secondary batteries and find usage in hybrid energy systems for electric vehicles, heavy-load starting assist for diesel locomotives, utility load leveling, and military and medical applications.9,10 Depending on the charge-storage mechanism, an ES is classified as an electrical double-layer capacitor ͑EDLC͒ or a pseudocapacitor. Higher energy density of EDLCs, as compared to dielectric capacit...

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Section: A76mentioning

confidence: 84%

Section: A76mentioning

confidence: 99%

mentioning

confidence: 99%

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Gelatin Hydrogel Electrolytes and Their Application to Electrochemical Supercapacitors

Choudhury¹,

Sampath

Shukla

2008

J. Electrochem. Soc.

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“…Ionic conduction in pristine GHE takes place by the Grö tthus-type mechanism of proton transport whereas that in NaCldoped GHEs occurs predominantly by free diffusion of hydrated Na + and Cl À ions. As described in the literature, 54 transport of protons in aqueous media by a Grö tthus-type mechanism takes place along chains of hydrogen bonded water molecules. In this mechanism, protons are transported by alternation of covalent and hydrogen bonds with little physical movement.…”

Section: Gelatin Hydrogel Electrolytesmentioning

confidence: 99%

Hydrogel-polymer electrolytes for electrochemical capacitors: an overview

Choudhury

Sampath

Shukla

2009

Energy Environ. Sci.

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372

260

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Electrochemical capacitors are electrochemical devices with fast and highly reversible charge-storage and discharge capabilities. The devices are attractive for energy storage particularly in applications involving high-power requirements. Electrochemical capacitors employ two electrodes and an aqueous or a non-aqueous electrolyte, either in liquid or solid form; the latter provides the advantages of compactness, reliability, freedom from leakage of any liquid component and a large operating potential-window. One of the classes of solid electrolytes used in capacitors is polymer-based and they generally consist of dry solid-polymer electrolytes or gel-polymer electrolyte or composite-polymer electrolytes. Dry solid-polymer electrolytes suffer from poor ionic-conductivity values, between 10 À8 and 10 À7 S cm À1 under ambient conditions, but are safer than gel-polymer electrolytes that exhibit high conductivity of ca. 10 À3 S cm À1 under ambient conditions. The aforesaid polymer-based electrolytes have the advantages of a wide potential window of ca. 4 V and hence can provide high energy-density. Gel-polymer electrolytes are generally prepared using organic solvents that are environmentally malignant. Hence, replacement of organic solvents with water in gel-polymer electrolytes is desirable which also minimizes the device cost substantially. The water containing gel-polymer electrolytes, called hydrogel-polymer electrolytes, are, however, limited by a low operating potential-window of only about 1.23 V. This article reviews salient features of electrochemical capacitors employing hydrogel-polymer electrolytes.

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“…Gel polymer electrolytes (GPE) Nagatomo et al, 1987;Peramunage et al, 1995) are capable of giving sufficient rigidity for enhancing device safety and provide much higher ionic conductivity than the polymeric solid electrolytes. There has recently been increasing interest in applying GPE to Ecs (Wada et al, 2004;Wada et al, 2006;Choudhury et al, 2006). More recently, a gel-type electrolyte has been tentatively applied in MnO 2 -based systems.…”

Section: Solid Electrolytesmentioning

confidence: 99%