Electric Double Layer Capacitors Research Articles

A Sustainable Li-Ion Capacitor Using Sawdust-Derived Activated Carbon Cathode Paired with Prelithiated Al Foil Anode

Activated carbon (AC) has long been recognized as a promising electrode material for energy storage/harvesting devices. The extraordinarily high specific area (e.g., ~2000 m2/g) makes AC almost irreplaceable in some applications, such as electrical double-layer capacitors (EDLCs) and capacitive deionization (CDI). [1] Yet the production of AC is often a concern due to the release of unwanted contaminants, such as waste acids and gaseous CO/CO2, resulting from a series of processes involving heating, burning, and the use of strong acids.In this work, we present an activated carbon cathode that is fabricated following a more sustainable approach, namely by using sawdust waste as the carbon precursor via a physical activation process to modify its surface area and porosity. With the electrochemical performances being characterized by designated cyclic voltammetry (CV), galvanostatic charge-discharge cycling (GCD), and electrochemical impedance spectroscopy (EIS), the activation parameters, such as temperature, activation time and activation gas composition, are expected to be optimized for various application purposes.To quickly demonstrate the technical feasibility, a high-performance Li-ion capacitor (LIC) is assembled using the sawdust-derived AC cathode to pair with a piece of prelithiated Al foil anode (β-LiAl). [2] Such an LIC is considered a hybrid energy storage device that can potentially combine the high energy density of a Li-ion battery with the high power density of a supercapacitor. Despite decent electrochemical performances, the proposed LIC device using a waste-derived cathode and a simple metallic foil anode can indeed help to better realize sustainability. [3] It is believed that such a unique LIC architecture can be a promising alternative to conventional energy storage devices for various applications, such as renewable energy storage, electric vehicles, and portable electronic devices.

A comprehensive study on effect of carbon nanomaterials as conductive additives in EDLCs

This study performs a comprehensive investigation to objectively analyze the effects of various carbon nanomaterials using as conductive additives (5 wt%) in activated carbon (AC) based electrodes for electrical double-layer capacitors (EDLCs). A variety of carbon nanomaterials including carbon black (CB), single-walled carbon nanotubes (SWCNT), graphene nanoplatelets (GNP), fullerenes (C60), and activated carbon nanofibers (ACNF) are considered in this work as they provide a diverse combination of intrinsic properties such as specific surface area, conductivity, micro-mesoporous structures, and geometry of nanomaterials. These additives are incorporated into freestanding carbon electrodes, and their EDLC performance in a neutral aqueous electrolyte is investigated by means of electrochemical measurements. The findings from this work provide useful insight into how the properties of various carbon nanomaterials influence EDLC performance in different aspects such as capacitive behavior, resistivity, performance at different current densities, charge propagation properties, and stability over long-term cycling. The results show that each carbon additive has its own strengths and limitations for different performance parameters considered. The unfavorable material properties of C60 cause a significant decrease in capacitance at high current density, leading to the lowest device performance incorporated with C60 as additives. While GNP and SWCNT show high crystallinity, low ID/IG ratios, the EDLCs still exhibit decreased specific capacitance and moderate energy densities due to their relatively limited specific surface area and high resistivity of the resultant composite electrodes compared to the pristine AC. The CB additives-based samples demonstrate the highest conductivity of dry electrodes and low equivalent series resistance (ESR) in EDLCs. On the other hand, a reduction in capacitance at high current densities and material degradation during long-term cycling are observed for CB samples, which could be attributed to the high dispersibility of CB causing limited interparticle voids and thus increasing diffusion resistance. In contrast, the use of ACNFs significantly reduces the diffusion resistance and improves the cyclic stability compared with CB based samples due to the advantages of larger specific surface area and superior micro-mesoporous structures of ACNFs. In particular, EDLCs with ACNFs demonstrate an increase in specific capacitance and energy density by 99 % and 76 %, respectively compared to CB based EDLCs at a current density of 20 A/g. This work elucidates the complex interplay between carbon nanomaterials using as additives and corresponding EDLC performance. These results provide important information to the community for future development of new energy conversion and storage devices.

Few-layer graphene as an ‘active’ conductive additive for flexible aqueous supercapacitor electrodes

We demonstrate that few layer graphene (FLG), formed by high-shear exfoliation into an aqueous suspension, can be successfully employed as an ‘active’ conductive additive in flexible activated carbon-based aqueous electric double layer capacitor (supercapacitor) electrodes if introduced by a novel ‘vacuum infiltration’ technique. The effectiveness of the FLG can be optimised by tailoring its size distribution and loading. It is found that best performance is achieved using FLG with the broadest size distribution and, moreover, that the larger size distribution is effective over the broadest range of loading. With optimum size distribution and loading, FLG is shown to outperform a commercial carbon black conductive additive (Timcal C65). Electrodes containing 8 wt% infiltrated FLG have an equivalent series resistance (ESR) of 1.3±0.4Ω, and a specific capacitance of 142.3±0.1 F g−1 over a voltage window of 1.2 V, compared with an ESR of 3±1Ω and a specific capacitance of 96.81±0.02 F g−1 for equivalent electrodes produced with an optimal loading of carbon black additive. As a result, the specific energy density of electric double layer capacitors (EDLCs) produced with a vacuum infused FLG additive is demonstrated to be an average of 47±3% superior to those containing carbon black measured at similar power densities. In contrast to vacuum infiltration, direct mixing of FLG suspension into the electrodes is found to be ineffective, resulting in limited improvement relative to electrodes without conductive additive, the reasons for which are discussed.

Optimizing Induction Wind Energy System with EDLC and PMSG for Efficient Power Control

This paper represents a comprehensive study on the optimization of an Induction Wind Energy System (IWEC) integrated with Electric Double Layer Capacitors (EDLCs) and a Permanent Magnet Synchronous Generator (PMSG) to enhance power control in the quest for sustainable and efficient energy conversion systems. As wind energy plays a pivotal role in the renewable energy landscape, maximizing its conversion efficiency is crucial for a sustainable future. Advanced control strategies and optimization techniques are applied to delve into the intricate details of the IWEC-EDLC-PMSG system, resulting in improved power quality, enhanced transient response, and superior grid integration capabilities. The research demonstrates that this integrated configuration outperforms conventional wind energy systems in terms of efficiency, grid compatibility, and dynamic response. Moreover, the study addresses key aspects like system stability, fault tolerance, and reliability, ensuring the robustness of this innovative solution. In addition to advancing wind energy technology, this research offers valuable insights into integrating energy storage systems and advanced control techniques for efficient power control in renewable energy applications, contributing to a sustainable energy future.

Methyl-orange/reduced graphene oxide composite as the electrode material for the solid-state supercapacitor

Abstract Herein, we have introduced the electrode material made up of a composite of an electrochemical active organic molecule (i.e. methyl orange (MO)) and reduced graphene oxide (rGO) composite. This composite is found to be a potential material for supercapacitor application due to the sustainability, redox reversibility of organic molecules, and good conductivity of rGO. For fabricating symmetric solid-state cell (MO/rGO//PVA/H2SO4//MO/rGO), polyvinyl alcohol–sulphuric acid (PVA/H2SO4) aqueous gel polymer electrolyte (GPE) has been sandwiched between the two MO/rGO electrodes. It was found that a MO/rGO based symmetric cell interfaced with a PVA/H2SO4 gel electrolyte has a specific capacitance of 166.79 F g−1 and an energy density of 11.58 Wh kg−1 at a power density of 6.25 kW kg−1. Here, good specific capacitance is the result of a combination of both electric double-layer capacitor (EDLC) and pseudo-capacitive behaviour observed in a fabricated cell. The specific capacitance is stable after 2500 cycles of charge and discharge, with an initial fade of 32 %. This synthesized material and fabricated device found its potential to be used for the supercapacitor application.

Rational design of pyrene and thienyltriazine-based conjugated microporous polymers for high-performance energy storage and visible-light photocatalytic hydrogen evolution from water

Conjugated microporous polymers (CMPs) have found extensive applications in various fields such as optoelectronics, CO2 capture, and catalysis. However, their potential in electrochemical supercapacitors as energy storage and H2 production systems remains relatively unexplored. This limited exploration can be attributed to certain challenges, including issues related to structural and electrochemical stability, as well as the relatively modest specific capacitance. Additionally, many of the CMPs discovered thus far have exhibited lower energy densities, further contributing to this underexplored aspect of their utility. In this study, we prepared two different CMPs [TPET-TTh and PyT-TTh CMPs] containing thienyltriazine units (TTh) for the redox mechanism and constructed electrodes for supercapacitor applications. The synthesized TPET-TTh and PyT-TTh CMPs displayed exceptionally high specific surface areas of 545 and 528 m² g⁻¹, respectively. Furthermore, their pore sizes were very similar, centered at approximately 0.39 and 0.36 nm, respectively. To evaluate their electrochemical properties, the TTh-CMPs were examined using cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The resulting CV curves exhibited rectangular shapes, indicative of the characteristic behavior of electric double-layer capacitors, across a range of potential and scan rates. These TPET-TTh and PyT-TTh CMPs delivered nominal specific capacitances of 74 and 76 F g−1 at 0.5 A g−1, respectively. In addition, they exhibited outstanding capacity retentions of 95.2 and 97.30 % even after 2000 cycles [analyzed at 10 A g−1]. The TTh-CMPs also exhibited excellent light-capture capabilities. The PyT-TTh CMP has faster charge separation and lower charge recombination rates than TPET-TTh CMP. This results in a higher hydrogen evolution rate from the water decomposition reaction. The H2 production rate of PyT-TTh CMP could be as high as 18,533 μmol g−1 h−1, which is approximately 4-fold that of TPET-TTh CMP. This study offers a strategy for the design of TTh-containing CMPs that exhibit exceptional energy storage application and photocatalytic efficiency for H2 evolution.

Facile Preparation of Petroleum Pitch-Based Activated Carbon with Open Macropore Walls for High Energy Density Supercapacitors

Electric double-layer capacitors have attracted considerable attention for energy storage because of their excellent power capability, high stability, and long cycle life. Activated carbon is the most widely employed electrode material for electric double-layer capacitors owing to its high specific surface area, hierarchical porous structure, and high electrical conductivity. However, to increase the energy density of the devices, new synthetic methods for enhancing their specific capacitances are required. We developed a facile preparation method for petroleum pitch-based activated carbon and investigated the optimal conditions to improve its electrochemical performance in terms of rate capability, specific capacitance, and cycle life. The obtained activated carbon exhibited a high specific capacitance (163.67 F/g at 0.1 A/g), which can be attributed to the efficient charge transport due to the micropores developed in the open macroporous walls of the carbon structure and the high electrical conductivity. Our approach provides an efficient strategy for synthesizing activated carbon with excellent properties. The results reveal a correlation between the physicochemical and electrochemical properties of activated carbon.

Analysis of voltametric data from electrochemical capacitor electrode materials: Method refinement for improved outcomes

A revised model is proposed to improve analysis outcomes from the voltametric analysis of electrochemical capacitor materials and electrodes at different sweep rates (v). Conventional analysis involves breaking down the voltametric current (i) into contributions from capacitive processes (i∝v) and diffusional processes (i∝v1/2). The proposed model introduces a resistance or residual current term, improving the goodness of fit and the quality of data interpretation. This is demonstrated by application of the revised model to artificial voltametric data, electrical double layer capacitor data, as well as pseudo-capacitive electrode data. Analysis with this model also demonstrates the importance of understanding resistive processes in electrode systems, in particular differentiating resistance in the act of charge storage (double layer and redox processes), and ohmic electrode resistance.

Identified potential of mangosteen peel agricultural waste as electrodes component of a supercapacitor: a study of electrochemical behaviour

Renewable porous carbon from lignocellulose material as the basic material for supercapacitors is of great interest to researchers because of its high application potential while solving environmental problems. Biomass-based lignocellulose components are the main choice because of the extraordinary impact on the carbon structure they get. Here, the identification of the potential of lignocellulose biomass from mangosteen cultivars as source material for electrode materials for supercapacitors has been studied on their electrochemical behaviour. The electro-physico-chemical features are reviewed in detail through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis at different ranges of scan rates and current densities. The obtained electrode was prepared by adding 10% polyvinyl alcohol binder to 0.7 gr carbon powder. The supercapacitor cell design is prepared in a symmetrical shape bounded by an organic separator. In general, the electrochemical properties of the electrode materials that have been obtained confirm the normal electrical double-layer capacitor features with an indication of the presence of apparent capacitance. The highest specific capacitance was 153.31 at 1 A g−1. Furthermore, the energy output was recorded of 1.67 Wh kg−1. These results confirm that an electrochemical study of mangosteen peel-based carbon materials has been successfully carried out for supercapacitor energy storage applications.

Electrochemical properties of a novel EDLC derived from plasticized biopolymer based electrolytes with valuable energy density close to NiMH batteries

This study introduces a novel system of solid electrolytes for electrical double-layer capacitors (EDLCs) utilizing biopolymer electrolytes with high energy density comparable to NiMH batteries. To prepare the electrolytes, a proton-conducting plasticized chitosan: poly(2-oxazoline) (POZ) with good film-forming properties was fabricated using a solution casting technique, and ammonium trifluoromethanesulfonate (NH4CF3SO3) salt was employed as a proton provider. Various glycerol concentrations were incorporated into the chitosan:POZ: NH4CF3SO3 system to enhance the ionic conductivity and fully transparent films were obtained. The impedance technique was utilized to determine the conductivity and measure the diffusion coefficient, mobility, and number density of ions. The electrochemical measurements, including linear sweep voltammetry (LSV) and cyclic voltammetry (CV), validated the high performance of the system. The EDLC was examined using galvanostatic charge-discharge (GCD) equipment, and the results revealed an energy density of 43 Wh/kg, specific capacitance of 300 F/g, and power density of 1800 W/kg over 500 cycles. These findings suggest that it is plausible to develop EDLCs that resemble batteries, making them a more desirable energy storage option for the industry.

Hard carbon-based electrode boosts the performance of a solid-state symmetric supercapacitor

Hard carbon materials have gained extensive utilization in energy storage systems because of their stable chemical properties, unique lamellar arrangement, and significant interlayer spacing. In this study, we present a novel porous carbon electrode based on hard carbon to enhance the performance of a solid-state symmetric supercapacitor. This electrode was fabricated through an efficient and straightforward synthetic approach using natural asphalt as the precursor. The resulting carbon electrode exhibits remarkable features including a large surface area (2334.48 m2 g−1), a well-distributed pore size (mesopore ratio of 16.04 %), an appropriate oxygen content (18.11 %), and a lamellar structure. As a result, the as-prepared carbon electrode demonstrates a high specific capacitance of 325.82 F g−1 at 0.5 A g−1, along with excellent rate capability, with coulombic efficiency ranging from 99.89 % at 0.5 A g−1 to 98.92 % at 10 A g−1. Moreover, the assembled symmetrical all-solid-state supercapacitor utilizing this electrode achieves an energy density of 18.91 Wh Kg−1, an equivalent series resistance of 0.820 Ω, a relaxation time of 9.0 s, and self-discharge performance lasting up to 72 h. Notably, owing to its large layer spacing (0.391 nm), the electric double layer capacitor contributes as much as 94 %, indicating favorable electrical double layer characteristics. Our work not only showcases a high-performance electrode material but also contributes to the expanded application of hard carbon.

Porous Carbon Nanosheets Derived from Spent Coffee Grounds for Highly Stable Electric Double-Layer Capacitors Enabled by Structurally Complementary Carbons

Porous Carbon Nanosheets Derived from Spent Coffee Grounds for Highly Stable Electric Double-Layer Capacitors Enabled by Structurally Complementary Carbons

High-Performance Li-Ion and Na-Ion Capacitors Based on a Spinel Li4Ti5O12 Anode and Carbonaceous Cathodes.

Lithium-ion hybrid capacitors (LICs) have become promising electrochemical energy storage systems that overcome the limitations of lithium-ion batteries and electrical double-layer capacitors. The asymmetric combination of these devices enhances the overall electrochemical performance by delivering simultaneous energy and power capabilities. Lithium titanate (Li4Ti5O12, LTO), a spinel zero-strain material, has been studied extensively as an anode material for LIC applications because of its high-rate capability, negligible volume change, and enhanced cycling performance. Here, the different synthetic methods and modifications of the intercalation-type LTO to enhance the overall electrochemical performance of LICs are mainly focused. Moreover, the cathodic part (i.e., the activated carbon derived from various sources, including natural products, polymers, and inorganic materials) is also dealt with as it contributes substantially to the overall performance of the LIC. Not only do the anode and cathode, but also the electrolytes have a substantial influence on LIC performance. The electrolytes used in LTO-based LICs as well as in flexible and bendable configurations are also mentioned. Overall, the previous work along with other available reports on LTO-based LICs in a simplified way is analyzed.

Clean energy storage device derived from biopolymers with moderate charge-discharge cycles: Structural and electrochemical properties

This work explores a green biopolymer (GBP) energy storage system to address the growing problem of microplastics that can harm our health. A GBP was made using solution casting with chitosan (CHN) and starch from potato (SPC) as the polymer hosts. Sodium thiocyanate (NaSCN) as Na+ cation provider and glycerol as an environmentally friendly plasticizer were mixed with CHN:SPC host polymers to prepare GBP electrolytes. The electrochemical impedance spectroscopy (EIS) results confirm the boost in DC conductivity. From the AC conductivity spectra, regions ascribing to EP and DC contributions are demonstrated. X-ray diffraction (XRD) and FTIR characterization provide evidence of salt dissociation and amorphous phase improvement. The determination of the ion fraction was achieved by means of TNM. The electrochemical stability of the conducting film was observed to be maintained up to 2.75 V. Cyclic voltammetry (CV), revealing no sign of charge transfer occurring through Faradaic processes at the interface between the electrode and electrolyte. The galvanostatic charge–discharge (GCD) plot displayed a triangular pattern, indicating a low voltage drop and a notable specific capacitance of 70 F/g. Moreover, the EDLC (electrical double-layer capacitor) exhibited an average power density of 1120 W/kg and an energy density of 9.11 Wh/kg.

A Dual-Functional MXene-Based Bioanode for Wearable Self-Charging Biosupercapacitors.

As a reliable energy-supply platform for wearable electronics, biosupercapacitors combine the characteristics of biofuel cells and supercapacitors to harvest and store the energy from human's sweat. However, the bulky preparation process and deep embedding of enzyme active sites in bioelectrodes usually limit the energy-harvesting process, retarding the practical power-supply sceneries especially during the complicated in vivo motion. Herein, a MXene/single-walled carbon nanotube/lactate oxidase hierarchical structure as the dual-functional bioanode is designed, which can not only provide a superior 3D catalytic microenvironment for enzyme accommodation to harvest energy from sweat, but also offers sufficient capacitance to store energy via the electrical double-layer capacitor. A wearable biosupercapacitor is fabricated in the "island-bridge" structure with a composite bioanode, active carbon/Pt cathode, polyacrylamide hydrogel substrate, and liquid metal conductor. The device exhibits an open-circuit voltageof 0.48V and the high power density of 220.9 µW cm-2 at 0.5mA cm-2 . The compact conformal adhesion with skin is successfully maintained under stretching/bending conditions. After repeatedly stretching the devices, there is no significant power attenuation in pulsed output. The unique bioelectrode structure and attractive energy harvesting/storing properties demonstrate the promising potential of this biosupercapacitor as a micro self-powered platform of wearable electronics.

Hierarchically Porous Carbon Networks Derived from Chitosan for High-Performance Electrochemical Double-Layer Capacitors.

Activated carbon (AC) compounds derived from biomass precursors have garnered significant attention as electrode materials in electric double-layer capacitors (EDLCs) due to their ready availability, cost-effectiveness, and potential for mass production. However, the accessibility of their active sites in electrochemistry has not been investigated in detail. In this study, we synthesized two novel macro/micro-porous carbon structures prepared from a chitosan precursor using an acid/potassium hydroxide activation process and then examined the relationship between their textural characteristics and capacitance as EDLCs. The material characterizations showed that the ACs, prepared through different activation processes, differed in porosity, with distinctive variations in particle shape. The sample activated at 800 °C (Act-chitosan) was characterized by plate-shaped particles, a specific surface area of 4128 m2/g, and a pore volume of 1.87 cm3/g. Assessment of the electrochemical characteristics of Act-chitosan showed its remarkable capacitance of 183.5 F/g at a scan rate of 5 mV/s, and it maintained exceptional cyclic stability even after 10,000 cycles. The improved electrochemical performance of both chitosan-derived carbon structures could thus be attributed to their large, well-developed active sites within pores < 2 nm, despite the fact that interconnected macro-porous particles can enhance ion accessibility on electrodes. Our findings provide a basis for the fabrication of biomass-based materials with promising applications in electrochemical energy storage systems.

Nanoporous Activated Carbon Material from Terminalia chebula Seed for Supercapacitor Application

High-surface-area porous carbon materials with high porosity and well-defined pore structures are the preferred advanced supercapacitors electrode materials. Here, we report the electrochemical supercapacitive performance of novel high-porosity activated carbon materials prepared from biowaste Terminalia chebula (Harro) seed stones involving zinc chloride (ZnCl2) activation. Activation is achieved by mixing ZnCl2 with Harro seed powder (1:1 w/w) followed by carbonization at 400–700 °C under a nitrogen gas atmosphere. The amorphous carbon materials obtained exhibit excellent performance as electrical double-layer capacitor electrodes in aqueous electrolyte (1 M sulfuric acid) due to high specific surface areas (as high as 1382.6 m2 g−1) based on well-developed micropore and mesopore structures, and partial graphitic structure containing oxygenated surface functional groups. An electrode prepared using material having the optimal surface textural properties achieved a large specific capacitance of 328.6 F g−1 at 1 A g−1 in a three-electrode cell setup. The electrode achieved a good capacitance retention of 44.7% at a high 50 A g−1 current density and outstanding cycling performance of 98.2% even following 10,000 successive charge/discharge cycles. Electrochemical data indicate the significant potential of Terminalia chebula seed-derived porous carbons as high-performance electrode materials for high-energy-storage supercapacitor applications.

Enhancing EDLC applications with [BMIM]BF4-integrated cellulose gel electrolyte for sustainable energy storage

Researchers worldwide have extensively carried out the fabrication of supercapacitors using ionic liquid-based gel electrolytes. Gel polymer electrolytes (GPEs) are an excellent alternative electrolyte due to their high ionic conductivity and lack of safety issues associated with solid and liquid polymer electrolytes. This work highlights the performance of a GPE composed of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]BF4 mixed with ammonium nitrate (NH4NO3) as the charge carrier, entrapped in methylcellulose (MC) for its application as an electrolyte in supercapacitors. The results of the Fourier transform infrared spectroscopy (FTIR) study are in good agreement with the literature, confirming the interaction between the materials observed through the shifting of the hydroxyl band. Moreover, the addition of [BMIM]BF4 successfully reduced the degree of crystallinity and crystallite size, thus enhancing the amorphous region of the electrolytes, as observed in the X-ray diffraction (XRD) diffractogram. The sample with 10 wt% [BMIM]BF4 (IL10) exhibits the highest ambient conductivity of (2.44 ± 0.36) × 10−2 S cm−1. The obtained ionic transference number (tion) of 0.98 confirms that ions are the dominant charge carriers. Considering its electrochemically stability up to 2.6 V within a potential range of 3.0 V, the IL10 electrolyte was chosen as a separator for application in an electric double-layer capacitor (EDLC). The EDLC is characterized via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis.

Symmetrical dialkyl-benzotriazolium as gel polymer electrolyte for energy storage and their alkyl chain trend on their electrochemical property

This work is on reporting development of symmetrically dialkylated series of benzotriazolium ionic liquids with tetrafluoroborate and hexafluorophosphate anion and their electrochemical properties. Also fabrication, and testing of ionic liquid as solid state gel polymer electrolyte using poly (vinylidenefluoride co hexa-fluoropropylene) as host polymer and testing their efficiency in electrical double layer capacitor. Structural characterizations done with 1H NMR, and 13C NMR and their property characterizations like electrochemical properties and the thermal properties of salts were done. All ionic liquids shows a potential window of ∼4.0 V. Cytotoxicity studies for understanding environmental friendliness of benzotriazolium ILs also studied using MTT assay which proved their alkyl chain effect on toxicity. The series of 1,3-dialkyl-1,2,3-benzotriazolium cationic and BF4ˉand PF6ˉ anionic ionic liquids shows are promising efficiency for energy storage application. Solid state gel polymer electrolyte using 1,3-dipropBTBF4 tested with symmetrical electrical double layer capacitor which shows 0–7.0 V excellent operating window. And at 0–3.5 V shows a good specific capacitance of 56.96 Fg−1 at scan rate of 2 mVs−1, and at a current density of 0.45 Ag−1 from galvanostatic charge discharge cycle a specific capacitance of 1.78 Fg−1 with energy density of 3.09 mWh and 509.45 mWg−1 power density. The prototype retains capacitance of 91.89 % even after 2000 cycles. Even after 2000 cycles the film stability is not much affected and resistance is not varied drastically. Single Swagelok cell charged at 2 V for 20 min was able to light red (1.7 V, 20 mA) LED brightly for 8 min, using two Swagelok cell charged individually up to 2 V for 20 min was enough to lit a blue LED of 2.7 V connected in series for 7 min brightly, which demonstrated its practical applicability. The unused IL remaining in the gel polymer electrolyte is easily and completely recovered out of the polymer host after studies which found to be advantages towards environmental friendliness in line with their disposal.

Microwaved-Assisted Synthesis of Starch-Based Biopolymer Membranes for Novel Green Electrochemical Energy Storage Devices.

The investigated starch biopolymer membrane was found to be a sustainable alternative to currently reported and used separators due to its properties, which were evaluated using physicochemical characterization. The molecular dynamics of the biomembrane were analyzed using low-field nuclear magnetic resonance (LF NMR) as well as Raman and infrared spectroscopy, which proved that the chemical composition of the obtained membrane did not degrade during microwave-assisted polymerization. Easily and cheaply prepared through microwave-assisted polymerization, the starch membrane was successfully used as a biodegradable membrane separating the positive and negative electrodes in electric double-layer capacitors (EDLCs). The obtained results for the electrochemical characterization via cyclic voltammetry (CV), galvanostatic charge with potential limitation (GCPL), and electrochemical impedance spectroscopy (EIS) show a capacitance of 30 F g-1 and a resistance of 2 Ohms; moreover, the longevity of the EDLC during electrochemical floating exceeded more than 200 h or a cyclic ability of 50,000 cycles. Furthermore, due to the flexibility of the membrane, it can be easily used in novel, flexible energy storage systems. This proves that this novel biomembrane can be a significant step toward ecologically friendly energy storage devices and could be considered a cheaper alternative to currently used materials, which cannot easily biodegrade over time in comparison to biopolymers.