Electrochemical Double Layer Capacitors Research Articles

Advancing supercapacitor performance: a comprehensive review of electrochemical conversion of coconut shells into activated carbon nanofibers

This assessment provides a comprehensive evaluation of the limitations associated with the application of supercapacitors, along with the imperative to enhance their functionality. Following this, the advantages of Electrochemical Double Layer Capacitors (EDLC) are discussed in comparison to other types utilized in supercapacitor contexts. The transformation of coconut shells into carbon nanofibers is extensively investigated through various methodologies, highlighting both their benefits and limitations. It becomes evident that the current utilization of coconut shells has not yet achieved optimal sustainability or viability for energy storage purposes. Nevertheless, coconut shells offer a widely available and sustainable resource that can be converted into Activated Carbon nanofibers for energy storage applications. Diverse techniques have been employed to produce these ACB nanofibers, each targeting specific objectives including improved energy density, adaptable diameter, reduced energy consumption, and faster charging times. Despite these accomplishments, it is evident that numerous significant properties of carbon nanofibers derived from coconut shells remain unexplored, leading to substantial knowledge gaps that must be addressed for each technique. Therefore, further research is warranted to advance the comprehension of key parameters associated with various methods, ultimately facilitating the development of highly desirable carbon nanofibers sourced from coconut shells and catering to the requirements of sustainable energy storage applications.

Optimizing EMIMBF4-based electrolyte with LiBr redox medium for enhanced supercapacitors

The formidable challenge of supercapacitors (SCs) is to achieve both high energy density and high power density simultaneously. Although the utilization of porous carbon materials for physical adsorption in electrochemical double-layer capacitors (EDLCs) applications exhibits promising prospects, attaining exceptional performance necessitates additional methodologies. Here, we propose an effective strategy for formulating redox electrolytes through the incorporation of organic solvents and LiBr into 1-ethyl-3-methylimidazole tetrafluoroborate (EMIMBF4) electrolytes. Within this formulation, LiBr serves as a redox mediator, contributing Br−/Br3− redox pairs to the system. The incorporation of EMIMBF4-LiBr-DMSO in brominated redox EDLCs led to a significant enhancement in specific capacitance, reaching up to 39.72 F g−1, representing a remarkable increase of 159 % compared to EDLCs without any redox media. This configuration achieved a high power density of 496.6 W kg−1 while maintaining an energy density of 34.48 Wh kg−1.

Preparation of V2O3 by a short process of ammonium salt reduction and its electrocatalytic properties investigation

Ammonium salt vanadium precipitation is the main method of vanadium metallurgy at home and abroad, but the traditional ammonium precipitation of vanadium can only obtain high valence of V2O5, and the NH3 produced in the calcination process cannot be fully utilized. And the preparation of low-valence vanadium oxide V2O3 is long and costly. Self-reduction of thermal decomposition of nitrogen-containing precipitation products to produce V2O3 is a novel and short process method that can achieve full utilization of ammonia. NaVO3 was used as the vanadium source, choline chloride (C5H14ClNO (ChCl)) was used as the vanadium precipitation reagent, and the vanadium concentration was 30 g/L, n(ChCl)/n(V) = 1.5, the initial pH was 1.5, the temperature was 85°C, the time was 2 h, and the vanadium precipitation efficiency could reach 97.05%. V2O3 with purity of 97.98% can be obtained by calcination at 550°C for 3 h in an argon atmosphere. XRD, FTIR, XPS, SEM-EDS were used to characterize the product, which further proved that the final product was V2O3. The electrocatalytic hydrogen evolution reaction (HER) of V2O3 in acidic media showed high stability after 1000 cyclic voltammetry (CV) cycles, with a low Tafel slope of 88.5 mVdec−1. The electrochemical double layer capacitance (EDLC) was measured by CV at different scan rates, and the EDLC of V2O3 was 1.104 mFcm−2. This study provides a short-flow preparation method for V2O3 and can provide predictions for the application of V2O3 in HER and supercapacitors.

In-situ synthesis of carbon-coated Mo2C: An exceptionally efficient and robust electrocatalyst for hydrogen evolution reaction (HER)

In the present work, the Mo2C electrocatalyst has been synthesized using waste plastic as carbon source. The use of plastic bottle has been chosen to reduce the cost of electrocatalyst as well to address the environmental issues caused due to these wastes. The pure phase sample was synthesized at 800 °C by carburizing MoO3 in an autoclave. The synthesized sample shows high activity towards HER with a lower Tafel slope of 85.7 mVdec−1. One of the exceptional features of the developed electrocatalyst is the long-term stability up to 7 days as determined by chronopotentiometry results. The improved activity and stability have been attributed to the presence of graphene like structures encapsulating the Mo2C particles. The presence of carbon also shows higher storage ability with an electrochemical double layer capacitance (EDLC, Cdl) of 91.0 μF. The synthesized sample shows an efficient and stable electrocatalyst towards HER.

Electron Delocalization and Electrochemical Potential Distribution Phenomena in Faradaic Electrode Materials for Understanding Electrochemical Behavior

AbstractElectrochemical energy storage devices are built upon the foudations of batteries and supercapacitors. In the past decade, new pseudocapacitor‐like electrodes are intensively developed to obtain superior energy storage performance. Pseudocapacitive matarials store charge through Faradaic processes, while the electrochemical signal remains like electrochemical double‐layer capacitors (EDLCs). To address this controversy, an analytical model is introduced for evaluating the voltammograms of electrode materials. Given this, the work focuses on understanding the origin of the pseudocapacitive phenomena in the cyclic voltammetry (CV) electrochemical signal. Based on electron transfer mechanism and tunnelling effect within the atomic structure, pseudocapacitive matarials possess a high electron delocalization possibility related to the redox centers number and initiates the electrochemical potential distribution among neighboring redox sites, which is consequently observed in the electrochemical signal as the plateau feature in CV, like EDLC. First, the determination of the capacitive tendency of various electrode materials is proposed, which turns out to be relative to the redox centers number (n) and total charge (Z). Here, when this number is large, electron hopping will very likely happen. The developed model is versatile to predict rate/potential regimes for the maximum faradaic storage, and then well differentiates the pseudocapacitive and battery materials.

Production and characterization of activated carbon foams with various activation agents for electrochemical double layer capacitors (EDLCs) applications

Sucrose-based activated carbons were obtained by carbon foams with sugar and cobalt (II) nitrate as precursors, followed by using different chemical activation agents. The effect of Co(NO3)2 concentration, the carbonization temperature and the activation agent on the surface chemistry, porosity were investigated. Textural characterization and electrochemical tests were performed on the activated carbon samples (CF). The results showed that the activated carbon produced by H2SO4 and KOH at 800°C had a surface area of 691 m2/g and 1125 m2/g, 89% and 80% of the sample pore structure was microporous, and specific capacitance of 8.4 F/g and 162.2 F/g at a constant current density of 250 mA/g, respectively. K2CO3-activated carbon had 918 m2/g surface area and 63% of the sample pore structure with microporous and 1.4 F/g specific capacitance, H3PO4-activated carbon and ZnCl2-activated carbon had 1833 m2/g and 1597 m2/g surface area, 53% mesoporous and 50% mesoporous, 222.4 F/g and 149.9 F/g specific capacitance respectively. The most promosing result was observed in the electrochemical storage behavior of the carbon materials with hierarchical pore structure activated with H3PO4 is associated with increasing defect zones at the edges of micro- and mesoporous morphology, resulting in a higher surface area and increased conductivity of the material.

A Review on Nano Fluid Production, Mathematical Modelling and Applications

Recently, nano fluids have taken on a significant role in many human endeavours. A fluid called a nanofluid includes nanoparticles, also called nanoparticles. Colloidal suspensions of nanoparticles in a base fluid are what these fluids are made of. The numerous production procedures and mathematical interpretation models for nanofluids are examined in this review study. Marangoni convection’s advantages, which enhance heat transfer and balance temperature distribution, are underlined. The effects of thermophoresis on surface tension as well as surface tension in laminar natural convection are also discussed in this work. The characteristics of carbon nanotubes and their prospective medical uses are covered in the article. The study covers electrochemical double layer capacitors, which offer greater safety, longer cycle stability, and better power densities. The study explores the impact of magnetic fields on entropy formation and natural convection in a hybrid nanofluid enclosure, revealing four distinct models based on thermal conductivity and viscosity correlations. The information review work is relevant. The review information work is relevant to flow tracers, prosthetic heart valves, oil pipelines, chemical industry separation methods, and oil recovery.

Interaction of electrolyte molecules with the surface of porous carbon: NMR study

Electrochemical double-layer capacitors use porous carbons as the electrode material, and improving their performance requires an understanding of the electrolyte−carbon surface interactions. 13C, 14N, and 11B NMR spectroscopy were used to investigate the behaviour of the electrolytes [C(OCH3)3NH3]+Cl- and [N(CH2CH3)]+BF4- on the surface of porous carbon in D2O solutions. A chemical shift of 13C has been found in the fragments N–C, indicating electron density redistribution between nitrogen atoms and alkyl fragments. The presence of a signal with a chemical shift of d = 7.7 confirms the structuring of the electrolytic layer of water solution [N(CH2CH3)]+BF4-.

Hydrogen-Assisted Thermal Treatment of Electrode Materials for Electrochemical Double-Layer Capacitors.

The capacitance of electrode materials used in electrochemical double-layer capacitors (EDLCs) is currently limited by several factors, including inaccessible isolated micropores in high-surface area carbons, the finite density of states resulting in a quantum capacitance in series to Helmholtz double-layer capacitance, and the presence of surface impurities, such as functional groups and adsorbed species. To unlock the full potential of EDLC active materials and corresponding electrodes, several post-production treatments are commonly proposed to improve their capacitance and, thus, the energy density of the corresponding devices. In this work, we report a systematic study of the effect of a prototypical treatment, namely H2-assisted thermal treatment, on the chemical, structural, and thermal properties of activated carbon and corresponding electrodes. By combining multiple characterization techniques, we clarify the actual origins of the improvement of the performance (e.g., > +35% energy density for the investigated power densities in the 0.5-45 kW kg-1 range) of the EDLCs based on treated electrodes compared to the case based on the pristine electrodes. Contrary to previous works supporting a questionable graphitization of the activated carbon at temperatures <1000 °C, we found that a "surface graphitization" of the activated carbon, detected by spectroscopic analysis, is mainly associated with the desorption of surface contaminants. The elimination of surface impurities, including adsorbed species, improves the surface capacitance of the activated carbon (CsurfAC) by +37.1 and +36.3% at specific currents of 1 and 10 A g-1, respectively. Despite the presence of slight densification of the activated carbon upon the thermal treatment, the latter still improves the cell gravimetric capacitance normalized on the mass of the activated carbon only (CgAC), e.g., + 28% at 1 A g-1. Besides, our holistic approach identifies the change in the active material and binder contents as a concomitant cause of the increase of cell gravimetric capacitance (Cg), accounting for the mass of all of the electrode materials measured for treated electrodes compared to pristine ones. Overall, this study provides new insights into the relationship between the modifications of the electrode materials induced by H2-assisted thermal treatments and the performance of the resulting EDLCs.

A rational study of transduction mechanisms of different materials for all solid contact-ISEs

The new era of solid contact ion selective electrodes (SC-ISEs) miniaturized design has received an extensive amount of concern. Because it eliminated the requirement for ongoing internal solution composition optimization and created a two-phase system with stronger detection limitations. Herein, the determination of venlafaxine HCl is based on a comparison study between different ion- to electron transduction materials (such as; multiwalled carbon nanotubes (MWCNTs), polyaniline (PANi), and ferrocene) and illustrating their mechanisms in their applied sensors. Their different electrochemical features (such as bulk resistance (Rb**), double-layer capacitance (Cdl), geometric capacitance (Cg), and specific capacitance (Cp)) were evaluated and discussed by using the Electrochemical Impedance Spectroscopy (EIS), Chronopotentiometry (CP), and Cyclic Voltammetry (CV) experiments. The results indicated that each transducer's influence on the proposed sensor's electrochemical characteristics is determined by their unique chemical and physical properties. The electrochemical features vary for different solid contact materials used in transduction mechanisms. The results confirm that the MWCNT sensor revealed the best electrochemical behavior with the potentiometric response of a near-Nernestian slope of 56.1 ± 0.8 mV/decade with detection limits of 3.8 × 10−6 mol/L (r2 = 0.999) and a low potential drift (∆E/∆t) of 34.6 µV/s. Also, the selectivity study was performed in the presence of different interfering species either in single or complex matrices. This demonstrates excellent selectivity, stability, conductivity, and reliability as a VEN-TPB ion pair sensor for accurately measuring VEN in its various formulations. The proposed method was compared to HPLC reported technique and confirmed no significant difference between them. So, the proposed sensors fulfill their solutions' demand features for VEN appraisal.

Cation desolvation-induced capacitance enhancement in reduced graphene oxide (rGO)

Understanding the local electrochemical processes is of key importance for efficient energy storage applications, including electrochemical double layer capacitors. In this work, we studied the charge storage mechanism of a model material - reduced graphene oxide (rGO) - in aqueous electrolyte using the combination of cavity micro-electrode, operando electrochemical quartz crystal microbalance (EQCM) and operando electrochemical dilatometry (ECD) tools. We evidence two regions with different charge storage mechanisms, depending on the cation-carbon interaction. Notably, under high cathodic polarization (region II), we report an important capacitance increase in Zn2+ containing electrolyte with minimum volume expansion, which is associated with Zn2+ desolvation resulting from strong electrostatic Zn2+-rGO interactions. These results highlight the significant role of ion-electrode interaction strength and cation desolvation in modulating the charging mechanisms, offering potential pathways for optimized capacitive energy storage. As a broader perspective, understanding confined electrochemical systems and the coupling between chemical, electrochemical and transport processes in confinement may open tremendous opportunities for energy, catalysis or water treatment applications in the future.

Mechanically Robust and Highly Conductive Poly(ionic liquid)/Polyacrylamide Double-Network Hydrogel Electrolytes for Flexible Symmetric Supercapacitors with a Wide Operating Voltage Range.

Flexible electronic devices, such as supercapacitors (SCs), place high demands on the mechanical properties, ionic conductivity, and electrochemical stability of electrolytes. Hydrogels, which combine flexibility and the advantages of both solid and liquid electrolytes, will meet the demand. Here, we report the synthesis of novel poly(ionic liquid)/polyacrylamide double-network (DN) (PIL/PAM DN) hydrogel electrolytes containing different metal salts via a two-step γ-radiation method. The resultant Li2SO4-1.0/PIL/PAM DN hydrogel electrolyte possesses excellent mechanical properties (tensile strength of 3.64 MPa, elongation at break of 446%) and high ionic conductivity (24.1 mS·cm-1). The corresponding flexible SC based on the Li2SO4-1.0/PIL/PAM DN hydrogel electrolyte (SC-Li2SO4) presents improved ion diffusion, ideal electrochemical double-layer capacitor behavior, good rate capability, and excellent cyclic stability. Moreover, symmetric SC-Li2SO4 achieves a wide operating voltage range of up to 1.5 V, with a maximum energy density of 26.0 W h·kg-1 and a capacitance retention of 94.1% after 10,000 galvanostatic charge-discharge cycles, owing to the deactivation of free water molecules by the synergistic effect of PIL, PAM, and SO42-. Above all, the capacitance of SC-Li2SO4 is well-maintained after overcharge, overdischarge, short circuit, extreme temperature, compression, and bending tests, indicating its high security and flexibility. This work reveals the enormous application potential of PIL-based conductive hydrogel electrolytes for flexible electronic devices.

High‐Strength Self‐Healable Supercapacitor Based on Supramolecular Polymer Hydrogel with Upper Critical Solubility Temperature

AbstractHere, poly(N‐acryloylglycinamide‐co‐vinyltriazole) p(NAGA‐co‐VTZ) supramolecular polymer hydrogel doped with carbonized and activated polypyrrole nanotubes as a high‐strength self‐healable material is presented for supercapacitors. Initially, the p(NAGA‐co‐VTZ) hydrogel films are synthesized by photopolymerization of N‐acryloylglycinamide and 1‐vinyl‐1,2,4‐triazole without the use of any cross‐linkers. The hydrogels demonstrated remarkable self‐healing ability via hydrogen bonding at temperatures above upper critical solubility temperature, excellent mechanical properties (0.86 MPa), large stretchability (1300%) and cut resistance. Subsequently, carbonized and ethanol/KOH‐activated polypyrrole nanotubes (acNTs) are prepared as the active material for electrochemical double‐layer capacitors (EDLC). Then, a symmetric self‐healable supercapacitor employing p(NAGA‐co‐VTZ) hydrogel, acNTs and aqueous 3 m KCl solution is assembled. Cyclic voltammetry and galvanostatic charge–discharge measurements show that the prepared device gives a specific capacitance of 282.62 F g−1 at 0.2 A g−1 and a high areal capacitance of 316.86 mF cm−2 at a scan rate of 10 mV s−1. Importantly, the supercapacitor operates over a wide voltage window (0–1.2 V) and provides excellent cyclic performance with capacitance retention of 97% after 10 000 cycles and 94% after self‐healing. In summary, the developed self‐healable supercapacitor exhibits considerable potential as a high‐performance energy storage device.

Tuning of Ionic Liquid–Solvent Electrolytes for High-Voltage Electrochemical Double Layer Capacitors: A Review

Electrochemical double-layer capacitors (EDLCs) possess extremely high-power density and a long cycle lifespan, but they have been long constrained by a low energy density. Since the electrochemical stability of electrolytes is essential to the operating voltage of EDLCs, and thus to their energy density, the tuning of electrolyte components towards a high-voltage window has been a research focus for a long time. Organic electrolytes based on ionic liquids (ILs) are recognized as the most commercially promising owing to their moderate operating voltage and excellent conductivity. Despite impressive progress, the working voltage of IL–solvent electrolytes needs to be improved to meet the growing demand. In this review, the recent progress in the tuning of IL- based organic electrolyte components for higher-voltage EDLCs is comprehensively summarized and the advantages and limitations of these innovative components are outlined. Furthermore, future trends of IL–solvent electrolytes in this field are highlighted.

Green polymer electrolyte and activated charcoal-based supercapacitor for energy harvesting application: Electrochemical characteristics

Abstract The aim of this study is to address the growing concern about microplastics in the ocean and their potential harm to human health through ingestion. The MPs issue is largely a result of the increasing demand for electronic devices and their components. To tackle this challenge, the research aimed to develop a green polymer electrolyte that used glycerol as a plasticizing agent to improve ionic conductivity. The polymer host included chitosan and polyvinyl alcohol and was composed of sodium acetate. To evaluate the performance of the polymer electrolyte, various analytical techniques were used, including impedance and electrochemical studies. The ionic conductivity of 7.56 × 10−5 S·cm−1 was recorded. The dielectric property study confirmed the ionic conduction process in the system and revealed the existence of non-Debye type relaxation, as indicated by asymmetric peaks of tanδ spectra. The alternating conductivity exhibits three distinguished regions. The polymer electrolyte was discovered to be electrochemically stable up to 2.33 V and capable of storing energy as a non-Faradaic electrochemical double-layer capacitor (EDLC). The cyclic voltammetry pattern is a leaf like shape. The EDLC was able to be charged and discharged up to 1 V, and it showed cyclability and could be used in low-voltage applications.

Structure and Electrical Properties of Polymer Electrolyte Based on Plasticized Chitosan Grafted Polymethyl Methacrylate (Ch-g-PMMA)- Magnesium Triflate for Electrochemical Double Layer Capacitor

Polymer electrolytes have received much attention as materials used in batteries, supercapacitors, sensors and solar cells. Most of the polymer electrolytes reported are based on synthetic polymer, therefore it is difficult to recycle as it has poor degradability and ends up being a waste. In recent years, biopolymers gained much interest in replacing environmentally unfriendly polymers. Various studies have been done to accomplish polymer electrolytes with high conductivity and long-term safety. This study’s objective is to prepare plasticized Ch-g-PMMA-based polymer electrolyte by introducing the magnesium triflate salt and glycerol plasticizer. The grafted polymer of Ch-g-PMMA was prepared using gamma (γ) radiation. The grafted polymer of Ch-g-PMMA with 0.4 g of Mg(Tf)2 and different concentrations of glycerol has been prepared by using the solution casting technique. To achieve this study, the prepared plasticized Ch-g-PMMA-Mg(Tf)2 polymer electrolytes are characterized by XRD, FTIR, EIS and LSV techniques. XRD was carried out to determine the change in crystallinity and the amorphous structure of the plasticized Ch-g-PMMA-Mg(Tf)2 polymer. FTIR reveals the occurrence of complexation between Ch-g-PMMA polymer, Mg(Tf)2 salt and glycerol plasticizer. The grafted Ch-g-PMMA-Mg(Tf)2 was added with different concentrations of glycerol from 0 to 50 wt%. The Ch-g-PMMA-Mg(Tf)2 polymer electrolyte with 50 wt% of glycerol shows the highest ionic conductivity of 1.50×10−4 S·cm−1 compared with other samples. The increase in mobility of ions and the number of charge carriers has enhanced ionic conductivity. Based on the LSV analysis, the highest conducting Ch-g-PMMA-Mg(Tf)2 polymer with 50 wt% of glycerol was found electrochemically stable up to 3.2 V. The goal of this study is to determine the structure and electrical properties as well as the window stability of plasticized Ch-g-PMMA-Mg(Tf)2. The best outcome was produced by adding the 50 wt% of glycerol into the Ch-g-PMMA-Mg(Tf)2 which increased further by 1 order of magnitude. HIGHLIGHTS The ionic conductivity of the Ch-g-PMMA increases by introducing magnesium triflate salt and glycerol plasticizer which enhance the amorphous state and decrease the crystallinity The prepared plasticized Ch-g-PMMA-Mg(Tf)2 polymer electrolytes are characterized by XRD, FTIR, EIS and LSV techniques The highest ionic conductivity are obtained by added 50 wt% glycerol to the grafted polymer CH-g-PMMA-Mg(Tf)2 which is 1.50×10−4 S·cm−1 GRAPHICAL ABSTRACT

Investigation of Several Bio Wastes as Sustainable Carbon Materials for Supercapacitor Manufacturing

This work presents various inquests on the utilization of bio wastes, agricultural wastes and sea shells to develop activated carbon as a veritable and sustainable electrode (terminals) substance for supercapacitors-(SC) also known as electrochemical double layer capacitors (EDLC) gadgets for preserving energy. We also looked at how electrode materials are processed with a view to improve or maximise the supercapacitor performance. This review entails how several bio wastes has been singed, synthesized and utilized to produce activated carbon material for long lasting, low-cost and environmentally-friendly EDLCs via the processes of pyrolysis, carbonization, physical activation and/or chemical activation with reagents and then characterized to show attributes making them suitable for application in supercapacitor manufacturing. Some of the features making the samples suitable for use as EDLC electrode materials include pore structure, very large surface area, power density, energy density, pore volume, cyclic stability specific capacitance, iodine adsorption with other attributes. This work also showcases how the various properties were determined by different tests including Brunauer-Emmett-Teller-(BET), Fourier Transform Infrared-(FTIR) Spectrometry, Field Emission Scanning Electron Microscopy-(FESEM), Raman-Spectroscopy, Scanning Electron Microscopy-(SEM), Energy Dispersive X-Ray-(EDX), X-Ray Diffraction-(XRD), TGA-Thermo-Gravimetric Analysis, Cyclic Voltammetry-(CV), Transmission Electron Microscopy-(TEM), and other procedures.

Water‐based Supercapacitors with Amino Acid Electrolytes: A Green Perspective for Capacitance Enhancement

AbstractState‐of‐the art Electrochemical Double‐Layer Capacitors (EDLCs) usually extend their operating electrochemical stability window (ESW) by means of organic electrolytes, or highly concentrated aqueous (water‐in‐salt) electrolytes hindering parasitic water splitting reactions. Unfortunately, organic solvents and high concentrations of ions penalize the dielectric constant of the electrolyte, hence the capacitive performance. We suggest here a new concept of cost‐effective and sustainable aqueous electrolytes based on concentrated amino acid water solutions with a dielectric permittivity much higher than pure water, unlocking the capacitive performance of aqueous EDLC references. Amino acids are natural zwitterionic molecules with a large separation between the positive and negative moiety, leading to huge dipoles with excellent dielectric properties. Some of them (e. g., lysine and proline), have a solubility 10 m at ambient temperature. With an experimental characterization we prove that aqueous EDLCs based on electrolytes obtained with L‐ lysine or L‐proline added to 2 M NaNO3 solution have +50 % of gravimetric capacitance enhancement at low specific currents (0.1 A/g) compared to a reference device based on 2 M NaNO3 electrolyte without amino acids. A theoretical model suggests that this performance may be further enhanced by increasing the ionic accessibility of commercially available active materials, with porosity optimized to the size of amino acid ions.

PEMBANGUNAN PENYIMPANAN TENAGA HIJAU DARIPADA SELULOSA BAKTERIA, SELULOSA METIL DAN KANJI KENTANG

A natural polymer known as bacterial cellulose (BC), derived from a symbiotic culture of bacteria and yeast (SCOBY), is utilized as the electrodes for the electrochemical double-layer capacitors (EDLC). Bacterial cellulose which can be easily obtained from the local market, possesses an exceptional structure that allows for the elimination of non-biodegradable binders and the use of current collectors in the EDLC electrodes. A green polymer electrolyte system consisting of methylcellulose, potato starch and lithium bromide. This electrolyte demonstrates a conductivity of (1.38 ± 0.54) × 10-4 S/cm, electrochemical stability of 1.3 V, and an ionic transference number of 0.98. The optimized electrolyte is used in the EDLC. Cyclic voltammetry analysis reveals that he fabricated EDLC has a capacitive behavior without any peaks indicating redox reactions. The EDLC undergo charging and discharging for up to 5000 cycles, with specific capacitances of 26 F/g. The EDLC shows a maximum power density of 1730 W/kg, with energy density of 3.6 Wh/kg.

Graphene Nanocomposite Materials for Supercapacitor Electrodes

Graphene and related materials (graphene oxide, reduced graphene oxide) as a subclass of carbon materials and their composites have been examined in various functions as materials in supercapacitor electrodes. They have been suggested as active masses for electrodes in electrochemical double-layer capacitors, tested as conducting additives for redox-active materials showing only poor electronic conductivity, and their use as a coating of active materials for corrosion and dissolution protection has been suggested. They have also been examined as a corrosion-protection coating of metallic current collectors; paper-like materials prepared from them have been proposed as mechanical support and as a current collector of supercapacitor electrodes. This entry provides an overview with representative examples. It outlines advantages, challenges, and future directions.