Organic Supercapacitors Research Articles

Graphitic porous carbon with multiple structural merits for high-performance organic supercapacitor

To circumvent the trade-off contradiction between porosity and graphitization of carbon materials for high-performance electrical double layer supercapacitors (EDLCs), we herein demonstrate a facile and effective solution by simultaneously achieving the etching reaction and graphitization process of a coal precursor with high carbon content and pre-formed graphite-like crystallites. The resulting graphitic porous carbon (AC-1000) exhibits simultaneously a high BET surface area up to 3214 m2 g−1 and a long-range graphitic network. In addition, AC-1000 also possesses a high packing density, low heteroatom and metal impurity contents (oxygen content less than 3.5 at.% and metal impurity less than 200 ppm) as well as an unprecedented production yield of 40%, all of which are highly desirable, but rarely achieved in reported porous carbons. The constructed organic supercapacitor delivers all-round improvements in capacitive performances in term of high capacitances (172 F g−1 at 0.5 A g−1 and 150 F g−1 at 30 A g−1), high energy density (37.2 Wh kg−1 at 303 W kg−1) and high power density (20.5 kW kg−1 at 25.3 Wh kg−1) as well as an excellent cycling stability of 10,000 cycles, markedly surpassing commercial activated carbon and showing application potential for commercial organic EDLCs.

A Self-standing Organic Supercapacitor to Power Bioelectronic Devices

The last decade has witnessed rapid progress in the development of implantable and wearable bio(chemical) sensors, which allow for real-time, continuous health monitoring. Among different device co...

Graphite Layer Coated on Aluminium Foil as Anti-corrosion Current Collector for Neutral Aqueous Supercapacitors

Neutral aqueous supercapacitors are of interest due to their many advantages such as low-cost, non-flammable, and high ionic conductivity. Interestingly, the current collector is a critical part of these devices since it can be corroded in aqueous electrolytes. The Al foil is a widely used current collector for commercial organic supercapacitors due to its low-cost. However, it is corroded in aqueous electrolytes. To address this issue, we develop the graphite coating layer on the Al current collector to suppress the corrosion of Al and the formation of an oxide-resistive film on Al in an aqueous electrolyte. The corrosion testing was confirmed by the electrochemical impedance spectroscopy (EIS). Furthermore, the electrochemical performance of the as-prepared electrodes with and without the graphite coated layer was studied by using cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The as-prepared electrode with a graphite protective layer exhibits a higher specific capacitance as well as a higher rate capability. The capacitance fading upon increasing scan rate from 10 mV s-1 to 100 mV s-1 of graphite coated aluminium electrode was only 15%, while the capacitance of the unmodified electrode extremely faded up to 75%. The as-prepared electrode with a graphite protective layer can explicitly improve the cycling stability (retain 90 %) after 5,000 cycles at an applied current density of 1 A g-1, which is different from an unmodified electrode with rapid fading up to 55%. This finding may lead to practical neutral aqueous supercapacitors.

Polydiacetylene-Perylenediimide Supercapacitors.

Organic supercapacitors have attracted interest as promising "green" and efficient components in energy storage applications. A polydiacetylene derivative coupled with reduced graphene oxide was employed, for the first time, to generate an organic pseudocapacitance-based supercapacitor that exhibited excellent electrochemical properties. Specifically, diacetylene monomers were functionalized with perylenediimide (PDI), spontaneously forming elongated microfibers. Following polymerization through UV irradiation, the PDI-polydiacetylene microfibers were interspersed with reduced graphene oxide (rGO), generating a porous electrode material exhibiting a high surface area and facilitating efficient ion diffusion, both essential preconditions for supercapacitor applications. We show that PDI-polydiacetylene has an important role in enhancing the electrochemical properties as a supercapacitor electrode. Besides stabilizing the microporous electrode organization, the delocalized π electrons in both the PDI residues and conjugated network of the polydiacetylene contributed to a significantly higher capacitance (specific capacitance >600 F g-1 at 1 A g-1 current density), longer discharge time, and high power density. The PDI-polydiacetylene-rGO electrodes were employed in a functional supercapacitor device.

Optimization of Micro-Scale Organic Energy Storage Devices

In pseudo-capacitors the energy storage process is due to fast, reversible faradic processes. For their higher specific capacitance with respect to conventional electrical double-layer capacitors that make use of high surface area carbons, these devices are among the most promising to provide high energy density and power necessary for modern and future applications. But the era of searching only for the best performance leaving environmental concerns is in the past: and now we have the moral obligation and responsibility of making every new technology evolving into sustainable and eco-friendly alternatives.Our group has achieved binder-free eco-friendly organic supercapacitors on different substrates such as carbon paper and polyethylene terephthalate (PET), using drop casting and microfabrication techniques, obtaining a specific capacitance of 167 Fg-1 on carbon paper, and 10.8 Fg-1 on flexible PET [1].In this work we optimize the microfabricated structure of flexible melanin-based electrodes by modifying the geometric architecture, maximizing the electrode/electrolyte interaction. Specifically, we report about the energy storage of flexible melanin-based micro-capacitors in aqueous electrolytes (NH4CH3COO(aq)).

An Electrochemically Stable 2D Covalent Organic Framework for High-performance Organic Supercapacitors

An electrochemically stable two-dimensional covalent organic framework, PI-COF, has been synthesized by a scalable solvothermal method. PI-COF possesses a highly crystalline structure, well-defined pores, high specific surface area, and cluster macrostructure. Thanks to these features, PI-COF can work as electrode materials in organic supercapacitors, exhibiting a specific capacitance of 163 F/g at 0.5 A/g over a wide potential window of 0–2.5 V. Moreover, PI-COF shows excellent rate performance, which can deliver 96 F/g even at a high current density of 40 A/g. Because of the high capacitance and wide potential window, PI-COF has achieved a superior energy density of 35.7 W·h/kg at a power density of 250 W/kg. Most importantly, due to the remarkable electrochemical stability, the PI-COF based device shows outstanding cycling stability with 84.1% capacitance maintained (137 F/g) after 3.0 × 104 charged/discharged cycles at 1 A/g. This work should shed light on designing new COF-based electrode materials for supercapacitors and other electrochemical devices.

Quinone‐Based Redox Supercapacitor Using Highly Conductive Hard Carbon Derived from Oak Wood

AbstractIn this study, the use of biorefined wood materials in the fabrication of organic redox supercapacitors is proposed. Oak‐derived hard carbon (HC) is revealed to have a nanographite domain structure, showing conductivity as high as that of artificial graphite. The CO2‐activated hard carbon (A–HC) has a conductivity one order higher than that of commercial activated carbon, with a surface area of 1126 m2 g−1. The energy densities of supercapacitors composed of a tetrachlorohydroquinone cathode and anthraquinone (AQ) or 1,5‐dichloroanthraquinone (DCAQ) anode are 19.0 and 13.8 Wh kg−1, respectively. The utilization rate of AQ with A–HC is 97.6% (250.9 mAh g−1), which is much higher than those in previous reports (≈80%). After 1000 cycles, 91.0% of the discharge capacity is retained when the DCAQ anode is used. Biorefined wood materials lead to a remarkable improvement in the operation of organic supercapacitors. This is intriguing, because the functional carbon material herein is easily prepared from a natural resource, wood, whereas numerous studies have prepared such materials from artificial chemical sources. Therefore, the use of oak‐derived HC enhances the usability of organic active materials for energy storage devices and potentially has a far‐reaching impact on the environment.

Solution blown polymer/biowaste derived carbon particles nanofibers: An optimization study and energy storage applications

Abstract The perspective of the abundant bio-materials and the possibility to be reused attracts attention, especially when producing carbon materials for energy storage applications. In that regard, an original electrode architecture is developed for symmetrical supercapacitor cells where peanut shell derived carbon particles are used to produce polymer/carbon fibrous electrodes. To obtain freestanding polymer/carbon electrodes, polyvinylidene fluoride (PVDF) nanofibers containing ultra-high amount of carbon nanoparticles are produced via solution blowing. Composite nanofiber production parameters such as polymer concentration, solvent ratio, and carbon concentration are optimized in order to obtain defectless fibers with the largest possible amount of carbon particles. It is found that 10wt% polymer solution, 60 wt% carbon content and 50:50 wt% DMF/acetone mixture are the optimized parameters. In the second part of the study, the produced fibrous materials are used in a symmetrical supercapacitor cell with aqueous and organic electrolytes. Aqueous supercapacitor cells with high electrode mass loading show areal capacitance up to 1120 mF cm−2. Moreover, fibrous electrodes with increased electrical conductivity show high rate capability at high currents and high cycling stability losing only 9% of its capacity after 10,000 cycles. The cycling stability of the electrodes is even more emphasized in organic supercapacitors where the cells retain 96.4% of their capacitance. The high surface area composite nanofibers are found to exhibit high energy and power values for both aqueous and organic supercapacitors. The proposed biowaste derived composition and fibrous architecture are thought to be highly promising due to high areal capacitance and stability.

Dielectric Properties of Dirt Sugarcane Sediment (DSS) Extract-BaTiO3 for Organic Supercapacitors

Filter cake (or Blotong) is a dirt sugarcane sediment (DSS) obtained from refining sugarcane. Organic Supercapacitors is a new technology combined battery and capacitor for advanced energy storage. The elements and compound containing in the DSS have potential be used as an electrode for supercapacitor. Firstly we prepared three different samples, i.e., heating at 100 °C for an hour, and addition method with H2SO4, and carbonation method at high temperatures. To control the specific capacitance, BaTiO3 nanoparticles fraction was added. It has been successfully fabricated with a structure of DSS/BaTiO3/aluminum films. This supercapacitor produces an average grain size of 31.81 ± 0.29 nm and porosity of 0.63. The capacitance and specific capacitance respectively reaches to 2.44 × 106 pF and 1100 × 106 pF/g.

Graphene Oxide Decorated Nanometal-Poly(Anilino-Dodecylbenzene Sulfonic Acid) for Application in High Performance Supercapacitors.

Graphene oxide (GO) decorated with silver (Ag), copper (Cu) or platinum (Pt) nanoparticles that are anchored on dodecylbenzene sulfonic acid (DBSA)-doped polyaniline (PANI) were prepared by a simple one-step method and applied as novel materials for high performance supercapacitors. High-resolution transmission electron microscopy (HRTEM) and high-resolution scanning electron microscopy (HRSEM) analyses revealed that a metal-decorated polymer matrix is embedded within the GO sheet. This caused the M/DBSA–PANI (M = Ag, Cu or Pt) particles to adsorb on the surface of the GO sheets, appearing as aggregated dark regions in the HRSEM images. The Fourier transform infrared (FTIR) spectroscopy studies revealed that GO was successfully produced and decorated with Ag, Cu or Pt nanoparticles anchored on DBSA–PANI. This was confirmed by the appearance of the GO signature epoxy C–O vibration band at 1040 cm−1 (which decreased upon the introduction of metal nanoparticle) and the PANI characteristic N–H stretching vibration band at 3144 cm−1 present only in the GO/M/DBSA–PANI systems. The composites were tested for their suitability as supercapacitor materials; and specific capacitance values of 206.4, 192.8 and 227.2 F·g−1 were determined for GO/Ag/DBSA–PANI, GO/Cu/DBSA–PANI and GO/Pt/DBSA–PANI, respectively. The GO/Pt/DBSA–PANI electrode exhibited the best specific capacitance value of the three electrodes and also had twice the specific capacitance value reported for Graphene/MnO2//ACN (113.5 F·g−1). This makes GO/Pt/DBSA–PANI a very promising organic supercapacitor material.

Communication—Introduction of Polyurethane-Polyacrylic Acid as a Binder for Electrochemical Activation of Expanded Mesocarbon Microbeads in Organic Supercapacitors

The electrochemical activation is a common technique enhancing the capacitive performances of carbons in high-voltage supercapacitors while volume expansion during the activation process often makes the active materials detachment, dropping the capacitance. In this work, the KOH-neutralized polyurethane-crosslinked-polyacrylic acid (PUPAH10-xKx) polymers are proposed to replace the polyvinylidene fluoride (PVDF) as a binder for expanded mesocarbon microbead (EMCMB) electrodes to buffer the volume expansion. The effects of binder rheology, morphology and neutralization degree on the capacitive performance of EMCMB are investigated. Introducing PUPAH6K4 with moderate viscoelasticity to EMCMB forms an expansion-buffering electrode and promotes the electrochemical activation process.

Design of organic supercapacitors with high performances using pore size controlled active materials

In this study, we thoroughly investigate the required properties of active materials for organic supercapacitors with high performances. In this regard, we synthesize carbon xerogels with different physical properties, including specific surface area and pore size. The carbon xerogels are prepared via the sol-gel reaction of resorcinol and formaldehyde under different gelation temperature conditions. Through Fourier-transform infrared, nitrogen adsorption–desorption, and scanning electron microscopy analysis, we can confirm that carbon xerogels with different physical properties can be successfully synthesized. We apply the prepared carbon xerogels to organic supercapacitor electrodes. As a result of electrochemical experiments, carbon xerogels with high surface area exhibit high electrochemical performances at low-rate charge−discharge processes. However, as the charge–discharge rate increases, carbon xerogels with low surface area and high conductivity exhibit higher performances. Therefore, the surface area of active materials is a key factor for supercapacitors with high performances at low-rate charge–discharge processes. However, the effects of conductivity can be more crucial as compared with those of surface area as the charge–discharge rates increase. In addition, we suggest that the physical properties of active materials should be differently optimized as the charge–discharge rate is employed.

High energy-density organic supercapacitors based on optimum matching between GNS/aMWCNT@polyaniline nanocone arrays cathode and GNS/aMWCNT@poly(1,5-diaminoanthraquinone) nanoparticles anode

Nowadays, high energy density is greatly imperative for supercapacitor technologies, which focus on both high-performance electrodes and assembling techniques. Here, we synthesized a promising cathode of graphene/acid-treated carbon nanotubes (GNS/aMWCNT)-supported polyaniline nanocone arrays by an interfacial polymerization, which achieves high specific capacitance of 299Fg−1 in 1M tetraethylammonium tetrafluoroborate-acetonitrile (Et4NBF4-AN) with the potential window of −0.6 to 0.8V (vs. Ag/Ag+). Matching it with GNS/aMWCNT-supported poly(1,5-diaminoanthraquinone) nanoparticles anode, the organic asymmetric supercapacitors (oASCs) are perfectly fabricated. The oASC with anode/cathode mass ratio of 1/1 delivers the highest energy density of 96.9Whkg−1, excellent rate capability (retain 65.6Whkg−1 even at 65.7kWkg−1) and superior cycling stability (94.2% retention after 5000 cycles), which is superior or comparable to other π-conjugated polymers-based organic supercapacitors.

Low temperature process of electronic charge transport mechanism in PANi/MWCNT nanocomposites: tubular morphology

In this work, we investigate the tuning of the electrical transport dimensionality of polyaniline-multiwalled carbon nanotube nanocomposites (PANi/MWCNTs) for electronic device applications. The microstructure and its correlations with electrical transport properties, and the conductivity of nanocomposites were studied from 75 to 330 K. The samples have been prepared with a new low-temperature system in which a layer of polymer has been coated on MWCNTs in a whole tubular morphology. The enhancement in conductivity of the nanocomposites is due to the charge transfer effect from the quinoid rings and the π-π interaction of the PANi to the MWCNT. The synthesized nanocomposites are investigated in the framework of existing theoretical models in 1, 2 & 3 dimensions (phonon assisted tunneling within the carbon nanotube and clusters) and systematically studied and compared in terms of transport parameters. Charge localization length and most probable hopping distance were found to decrease with wt% of MWCNT, whereas the charge hopping energy increases in nanocomposites. The distinction between thermally activated processes and the determination of cross-over temperature were achieved by exploring the temperature dependence of the fractional exponent of the dispersive conductivity. The enhanced transport properties of these categories of nanocomposites due to a combination of MWCNTs in conducting polymer matrix can be applied for photodetectors, organic solar cells, supercapacitors, and electronic strategies.

A study of fused-ring thieno[3,4-e]pyrazine polymers as n-type materials for organic supercapacitors

Conjugated polymer pseudocapacitors achieve high capacitances because they store charge through fast, reversible redox reactions.

Effect of Conductive Additive Amount on Electrochemical Performances of Organic Supercapacitors

In this study, we intensively investigated the effect of conductive additive amount on electrochemical performance of organic supercapacitors. For this purpose, we assembled coin-type organic supercapacitor cells with a variation of conductive additive(carbon black) amount; carbon aerogel and polyvinylidene fluoride were employed as active material and binder, respectively. Carbon aerogel, which is a highly mesoporous and ultralight material, was prepared via pyrolysis of resorcinolformaldehyde gels synthesized from polycondensation of two starting materials using sodium carbonate as the base catalyst. Successful formation of carbon aerogel was well confirmed by Fourier-transform infrared spectroscopy and N2 adsorptiondesorption analysis. Electrochemical performances of the assembled organic supercapacitor cells were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements. Amount of conductive additive was found to strongly affect the charge transfer resistance of the supercapacitor electrodes, leading to a different optimal amount of conductive additive in organic supercapacitor electrodes depending on the applied charge-discharge rate. A high-rate charge-discharge process required a relatively high amount of conductive additive. Through this work, we came to conclude that determining the optimal amount of conductive additive in developing an efficient organic supercapacitor should include a significant consideration of supercapacitor end use, especially the rate employed for the charge-discharge process.

Electrochemical Capacitor of MnFe2O4 with Organic Li-Ion Electrolyte

Compared with batteries, electrochemical capacitors have the potential for providing higher power density and good cyclability. Pseudocapacitance results from either superficial or multi electron-transfer faradaic reactions with fast charge/discharge properties. An increasing number of metal oxides exhibiting pseudocapacitive behaviors have been discovered in recent years. We have previously discovered a new nanocrystalline oxide material having the formula of MnFe2O4that have so far been the only oxide electrode showing pseudocapacitance in both aqueous and organic Li-ion electrolytes. The discovery of this material has opened up the possibility of setting up a high voltage asymmetric supercapacitors of substantially enhanced energy density over the state-of-the-art EDLC organic supercapacitors. In this study, MnFe2O4 spinel oxide electrodes was synthesized and characterized for supercapacitor applications using organic Li-ion electrolyte. The change in structure, valence state and local atomic arrangement upon charging/discharging are investigated with in operando X-ray analyses. The operation voltage window is carefully determined in view of leakage current for the upper voltage limit. The lower voltage window is selected to maximize the energy density of the spinel oxide electrode. For the purpose of increasing the energy density of cell up for the demand of electronic devices, asymmetric capacitor is assembled using the spinel oxide as positive electrode and pre-lithiated silicon coated graphite (SGF) as negative electrode. It is shown that the asymmetric capacitor has greatly increased the energy density by asymmetric mass matching between anode and cathode and by extending the overall operation voltage window. Figure 1

Ultrafast growth of carbon nanotubes on graphene for capacitive energy storage

We have demonstrated a novel three-dimensional (3D) architecture of a graphene/carbon nanotube (G-CNT) hybrid synthesized at large scale within just 5 s via a simple microwave-heating method without the usage of any other conducting or expanding agent for the first time. The carbon composites obtained consist of evenly grown CNTs with an average diameter of about 15 nm on the surface of graphene nanosheets. The G-CNT hybrid exhibits enhanced electrochemical performance for both aqueous and organic supercapacitor devices. Particularly, the G-CNT electrodes demonstrate an enhanced specific capacitance of 361 F g−1 at a current density of 1.1 A g−1 in an aqueous electrolyte and a volumetric capacitance of 254 F cm−3 in an organic electrolyte. They also display excellent cycle stability with nearly 91.2% of the initial capacitance retained after 10 000 charging-discharging cycles at a current density of 15 A g−1. This demonstrates that the developed composites have potential applications in supercapacitors and other energy storage devices.

A graphene/carbon nanotube@π-conjugated polymer nanocomposite for high-performance organic supercapacitor electrodes

An intriguing organic supercapacitor based on hierarchical porous GNS/aMWCNT@poly(1,5-diaminoanthraquinone) is fabricated with superhigh energy density and excellent cycling stability.

Low Temperature Syntheses of Transition Metal Bronzes with an Open Structure for High Rate Energy Storage

ABSTRACTDevelopment of devices storing and delivering high-energy power such as supercapacitors is necessary to assist intermittent sources of energy. Most of the commercial systems are carbon-based, but due to their high surface charge, oxides offer a valuable alternative for high-rate energy storage. Among them, layered transition metal oxides with mixed valence properties present both good electronic and ionic conductivities suitable for application to electrochemical applications intermediate between capacitors and batteries. This work focuses on lamellar oxide bronzes based on cobalt MxCoO2 and vanadium MxV2O5 (M = H, Li, Na or K). A low temperature synthesis leads to high specific area particles (above 100 m2/g). Hydrated and anhydrous NaxCoO2 are promising cathode materials for aqueous supercapacitors, with a high capacity of more than 100 mAh/g obtained under 20 mV/s for the hydrated NaxCoO2. The MxV2O5 bronzes appear to be good candidates for organic supercapacitors, especially the LixV2O5 bronze, which shows a high stable capacity above 100 mAh/g (at 20 mV/s ie a charging time of 125 s).