An Experimental Research on Electrochemical Impedance Spectra of New High-Specific Energy EDLC

The real times Electrochemical Impedance Spectroscopy (EIS) analysis which corresponds to the charge and discharge process was reported in order to evaluate the relationships between impedance and potential for new high specific energy electrochemical double-layer capacitors (EDLC). Also the Niquist plots were presented and the impedance of the EDLC was discussed in terms of complex capacitance. It was found that the high frequency impedance changed with its potential in charging or discharging process, the medium frequency impedance Rct belonged to the resistance of ions diffusion into micro pore or the inner of electrode material decreased with increasing charge voltage and had a certain capacitance of about 1F.

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High Performance Graphene-Based Electrochemical Double Layer Capacitors Using 1-Butyl-1-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate Ionic Liquid as an Electrolyte

Electronics ◽

10.3390/electronics7100229 ◽

2018 ◽

Vol 7 (10) ◽

pp. 229 ◽

Cited By ~ 4

Author(s):

Jacob D. Huffstutler ◽

Milinda Wasala ◽

Julianna Richie ◽

John Barron ◽

Andrew Winchester ◽

...

Keyword(s):

Ionic Liquid ◽

Energy Density ◽

Double Layer ◽

Specific Energy ◽

High Energy ◽

High Energy Density ◽

Electrochemical Double Layer Capacitors ◽

Electrochemical Double Layer ◽

High Specific Energy ◽

Double Layer Capacitors

There are several advantages to developing electrochemical double-layer capacitors (EDLC) or supercapacitors with high specific energy densities, for example, these can be used in applications related to quality power generation, voltage stabilization, and frequency regulation. In this regard, ionic liquids capable of providing a higher voltage window of operations compared to an aqueous and/or polymer electrolyte can significantly enhance the specific energy densities of EDLCs. Here we demonstrate that EDLCs fabricated using ionic liquid 1-butyl-1-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate (BMP-FAP) as an electrolyte and few layer liquid-phase exfoliated graphene as electrodes show remarkable performance compared to EDLC devices fabricated with aqueous potassium hydroxide (6M) as well as widely used ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). We found that graphene EDLC’s with BMP-FAP as an electrolyte possess a high specific energy density of ≈25 Wh/kg along with specific capacitance values as high as 200 F/g and having an operating voltage windows of >5 volts with a rapid charge transfer response. These findings strongly indicate the suitability of BMP-FAP as a good choice of electrolyte for high energy density EDLC devices.

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Cobalt Sulfide-Graphene (CoSG) Composite based Electrochemical Double Layer Capacitors

MRS Proceedings ◽

10.1557/opl.2015.784 ◽

2015 ◽

Vol 1786 ◽

pp. 19-30 ◽

Cited By ~ 1

Author(s):

R Ramachandran ◽

Grace A Nirmala ◽

Chittur K Subramaniam

Keyword(s):

Double Layer ◽

Polyvinylidene Fluoride ◽

Electrochemical Impedance ◽

Electrochemical Techniques ◽

Cobalt Sulfide ◽

Composite Electrodes ◽

Electrode Structure ◽

Electrochemical Double Layer Capacitors ◽

Electrochemical Double Layer ◽

Double Layer Capacitors

ABSTRACTElectrochemical Double Layer Capacitors, EDLC, using Cobalt sulfide- Graphene (CoSG) composite electrodes, were fabricated and the storage process was studied. CoSG composite was prepared by a simple chemical route. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Field Emission Scanning Electron microscopy (FESEM) were used to characterized the as prepared composites which indicated formation of Co S phase. Solutions of perfluorosulfonic acid and Polyvinylidene Fluoride (PVDF) were used as electrode binding material. The storage capacitance of the composites were studied in 1M KCl and 6M KOH electrolytes using standard electrochemical techniques like cyclic voltammetry, CV, electrochemical impedance spectroscopy, EIS, and discharge profiles. The capacitance was estimated for various binder concentrations for both the electrolytes. The concentration of perflurosulfonic acid binder of 0.8 wt% and PVDF of 0.04 wt% showed optimized specific capacitances of 657.8 F/gm and 1418.8 F/g, respectively. Some of the problems in storage density in activated carbon, like varying micro or meso pores, poor ion mobility due to varying pore distribution, low electrical conductivity, can be overcome by using Graphene and composites of Graphene. Graphene in various structural nomenclatures have been used by different groups for charge storage. Optimization of the electrode structure in terms of blend percentage, binder content and interface character in the frequency and time domain provides insights to the double layer interface structure.

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Defect Engineered Multi-Walled Carbon Nanotube arrays as Electrochemical Double Layer Capacitors

MRS Proceedings ◽

10.1557/opl.2013.602 ◽

2013 ◽

Vol 1542 ◽

Author(s):

Rajaram Narayanan ◽

Mark Hoefer ◽

Prabhakar R. Bandaru

Keyword(s):

Carbon Nanotube ◽

Double Layer ◽

Electrochemical Impedance ◽

Electrochemical Techniques ◽

Argon Plasma ◽

Plasma Irradiation ◽

Multi Walled Carbon Nanotube ◽

Electrochemical Double Layer Capacitors ◽

Electrochemical Double Layer ◽

Double Layer Capacitors

ABSTRACTThe efficacy of vertically aligned defect engineered multi-walled carbon nanotube (MWCNT) arrays as electrochemical double layer capacitors (EDLCs) was investigated using standard electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). We report a ∼ 200% improvement in specific double layer capacitance of MWCNT arrays by extrinsically introducing defects using argon plasma irradiation. The capacitance-voltage characteristics of argon irradiated MWCNTs provide insights into the nature of the defects and their influence on the specific capacitance (capacitance/area).

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Ionic Liquids as Electrolytes for Electrochemical Double-Layer Capacitors: Structures that Optimize Specific Energy

ACS Applied Materials & Interfaces ◽

10.1021/acsami.5b11353 ◽

2016 ◽

Vol 8 (5) ◽

pp. 3396-3406 ◽

Cited By ~ 94

Author(s):

Maral P. S. Mousavi ◽

Benjamin E. Wilson ◽

Sadra Kashefolgheta ◽

Evan L. Anderson ◽

Siyao He ◽

...

Keyword(s):

Ionic Liquids ◽

Double Layer ◽

Specific Energy ◽

Electrochemical Double Layer Capacitors ◽

Electrochemical Double Layer ◽

Double Layer Capacitors

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A Study on Oxidized Glassy Carbon sheets for Bipolar Supercapacitor Electrodes

MRS Proceedings ◽

10.1557/proc-575-369 ◽

1999 ◽

Vol 575 ◽

Cited By ~ 3

Author(s):

A. Braun ◽

M. Bärtsch ◽

F. Geiger ◽

B. Schnyder ◽

R. Kötz ◽

...

Keyword(s):

Double Layer ◽

Glassy Carbon ◽

Gas Adsorption ◽

Electrochemical Impedance ◽

High Energy ◽

Active Film ◽

X Ray Scattering ◽

Electrochemical Double Layer Capacitors ◽

Electrochemical Double Layer ◽

Double Layer Capacitors

ABSTRACTElectrochemical Double Layer Capacitors (EDLC) for high energy and power density applications, based on glassy carbon (GO) electrodes, are being developed in our laboratory. In the context of this project, GC sheets were oxidized and investigated with Small Angle X-ray Scattering (SAXS), Electrochemical Impedance Spectroscopy (EIS) and Nitrogen Gas Adsorption (BET). During oxidation an active film with open pores is built on the surface of the GC. Upon oxidation, the internal volumetric surface area of the active film decreases, whereas the volumetric electrochemical double layer capacitance increases. We show that this effect is correlated with the opening, the growth and the coalescence of the pores.

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