• Title, Summary, Keyword: Electrochemical supercapacitors

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Recent Advances on Multi-Dimensional Nanocarbons for Superapacitors: A Review

  • Bae, Joonho
    • Journal of Electrochemical Science and Technology
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    • v.9 no.4
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    • pp.251-259
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    • 2018
  • In general, the charge storage characteristics and overall performance of electrochemical energy devices (such as lithiumion batteries and supercapacitors) significantly depends on the structural and geometrical factors of the electrodes' active materials. The most widely used active materials of electrochemical energy storage devices are based on carbons of various forms. Each carbon type has drawbacks and advantages when used as the electrode material. Studies have been recently carried out to combine different types of carbons, in particular nanostructured carbons, in order to overcome the structure-originated limitations and thus enhance the overall electrochemical performances. In this feature article, we report the recent progress on the development of this novel class of materials (multidimensional nanocarbons), and their applications for supercapacitors. Multidimensional nanocarbons include graphenes/carbon nanotubes (CNTs), CNTs/carbon films, CNTs/fullerenes, and ternary carbon nanostructures. Various applications using these multidimensional nanocarbons have been proposed and demonstrated in the literature. Owing to the recent extensive studies on electrochemical energy storage devices and considering that carbons are their most fundamental electrode materials, the number of reports on nanocarbons employed as electrodes of the electrochemical energy storage devices is rapidly increasing. Recently, numerous multidimensional nanocarbons have been designed, prepared, and utilized as electrodes of electrochemical capacitors or supercapacitors, which are considered next-generation energy devices owing to their unique merits compared to the conventional structures. In this review, we summarize the basic motivations, preparation methods, and resultant supercapacitor performances of each class of multidimensional nanocarbons published in the literature, focusing on recent reports.

Novel Flexible Supercapacitors Fabricated by Simple Integration of Electrodes, Binders, and Electrolytes into Glass Fibre Separators

  • Yoo, Joung Eun;Bae, Joonho
    • Journal of the Korean Electrochemical Society
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    • v.17 no.4
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    • pp.237-244
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    • 2014
  • We report novel and simple structure of supercapacitors fabricated by using flexible glass fibre separators as templates. This method does not require separate electrodes, binders and high pressure/temperature to build the supercapacitor unit cells as required by the conventional technology. The supercapacitors were fabricated by drop-casting solution mixtures of carbonaceous active materials/gel electrolytes onto two sides of glass fibre separators. Two carbonaceous materials (nanoscaled activated carbons, multi-walled carbon nanotubes) were investigated as electrode materials. The electrochemical measurements reveal that the separatorbased supercapacitors using ACs successfully demonstrated significant mass specific capacitance ($22.3F\;g^{-1}$) and energy density ($9.7Wh\;kg^{-1}$), indicating this method can be useful in fabricating flexible, wearable and stretchable energy storage devices in more straightforward and cost-effective way than current technology.

Electrochemical Behavior Depending on Designed-Anode and Cathodes of Hybrid Supercapacitors (하이브리드 슈퍼커패시터의 음극 및 양극 설계에 따른 전기화학적 거동)

  • Shin, Seung-Il;Lee, Byung-Gwan;Ha, Min-Woo;An, Geon-Hyoung
    • Korean Journal of Materials Research
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    • v.29 no.12
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    • pp.774-780
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    • 2019
  • The performance of Li-ion hybrid supercapacitors (asymmetric-type) depends on many factors such as the capacity ratio, material properties, cell designs and operating conditions. Among these, in consideration of balanced electrochemical reactions, the capacity ratio of the negative (anode) to positive (cathode) electrode is one of the most important factors to design the Li-ion hybrid supercapacitors for high energy storing performance. We assemble Li-ion hybrid supercapacitors using activated carbon (AC) as anode material, lithium manganese oxide as cathode material, and organic electrolyte (1 mol L-1 LiPF6 in acetonitrile). At this point, the thickness of the anode electrode is controlled at 160, 200, and 240 ㎛. Also, thickness of cathode electrode is fixed at 60 ㎛. Then, the effect of negative and positive electrode ratio on the electrochemical performance of AC/LiMn2O4 Li-ion hybrid supercapacitors is investigated, especially in the terms of capacity and cyclability at high current density. In this study, we demonstrate the relationship of capacity ratio between anode and cathode electrode, and the excellent electrochemical performance of AC/LiMn2O4 Li-ion hybrid supercapacitors. The remarkable capability of these materials proves that manipulation of the capacity ratio is a promising technology for high-performance Li-ion hybrid supercapacitors.

Novel P(VDF-TrFE) Polymer Electrolytes: Their Use in High-Efficiency, All-Solid-State Electrochemical Capacitors Using ZnO Nanowires

  • Park, Young Jun;Bae, Joonho
    • Journal of Electrochemical Science and Technology
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    • v.9 no.2
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    • pp.126-132
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    • 2018
  • For the first time, an innovative approach using P(VDF-TrFE) as a polymer electrolyte for high efficiency, all-solid-state supercapacitors is presented. The polymer electrolyte was successfully achieved by dissolving P(VDF-TrFE) copolymers in dimethylformamide (DMF). Thermal analysis and infrared spectroscopy revealed excellent thermal stability up to $400^{\circ}C$ and copolymer's interaction with DMF. Electrochemical capacitors fabricated using P(VDF-TrFE) in DMF and ZnO NWs demonstrated high capacitive performance. Furthermore, the gel electrolyte-based supercapacitors demonstrated excellent mechanical durability up to a bend angle of $120^{\circ}$. Novel P(VDF-TrFE) electrolytes could be a promising approach for applications in flexible, fabric-based, and high-efficiency energy devices.

Volumetric Capacitance of In-Plane- and Out-of-Plane-Structured Multilayer Graphene Supercapacitors

  • Yoo, Jungjoon;Kim, Yongil;Lee, Chan-Woo;Yoon, Hana;Yoo, Seunghwan;Jeong, Hakgeun
    • Journal of Electrochemical Science and Technology
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    • v.8 no.3
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    • pp.250-256
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    • 2017
  • A graphene electrode with a novel in-plane structure is proposed and successfully adopted for use in supercapacitor applications. The in-plane structure allows electrolyte ions to interact with all the graphene layers in the electrode, thereby maximizing the utilization of the electrochemical surface area. This novel structure contrasts with the conventional out-of-plane stacked structure of such supercapacitors. We herein compare the volumetric capacitances of in-plane- and out-of-plane-structured devices with reduced multi-layer graphene oxide films as electrodes. The in-plane-structured device exhibits a capacitance 2.5 times higher (i.e., $327F\;cm^{-3}$) than that of the out-of-plane-structured device, in addition to an energy density of $11.4mWh\;cm^{-3}$, which is higher than that of lithium-ion thin-film batteries and is the highest among in-plane-structured ultra-small graphene-based supercapacitors reported to date. Therefore, this study demonstrates the potential of in-plane-structured supercapacitors with high volumetric performances as ultra-small energy storage devices.

Electrochemical characterization of supercapacitors based on carbons derived from Sorona activated by ZnCl2

  • Jisha, M.R.;Christy, Maria;Kim, Ae Rhan;Nahm, Kee Suk;Yoo, Dong Jin
    • Journal of Energy Engineering
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    • v.21 no.3
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    • pp.309-314
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    • 2012
  • Carbons derived by the pyrolysis of Sorona activated by $ZnCl_2$ in the ratio of 1:20 and non-porogen Sorona carbons are used as the electrode materials in asymmetric electrochemical supercapacitors and electrochemical behavior is investigated. Scanning electron microscopy (SEM) reveals the porogen free carbons show a flake-like structure and the $ZnCl_2$-treated Sorona carbons have a loose, disjoint structure without any particular shape. Cyclic voltammetric (CV) studies show specific prolate rectangular shape and gives good capacitive properties.

Preparation and Electrochemical Characteristics of DAAQ/CNFs Composite electrode for Supercapacitor (DAAQ가 코팅된 슈퍼커패시터용 CNFs전극 활물질의 제조 및 전기 화학적 특성)

  • Kim, Hong-Il;Choi, Weon-Kyung;Park, Soo-Gil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.1226-1229
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    • 2004
  • Supercapacitors, also known as electrochemical capacitors, are being extensively studied due to an increasing demand for energy-storage systems. These devices offer many advantages over conventional secondary batteries, which include the ability of fast charge propagation, long cycle-life and better storage efficiency. That is to say supercapacitor bridges the gap between conventional capacitors and batteries. A new type electric double layer capacitor (EDLC) also called supercapacitors. Recently, supercapacitors concerns about their high power density and energy density. So we experiment with EDLC by using carbon nanofibers (CNFs) and DAAQ(1,5-diaminoanthraquinone) electrode. The electrode for supercapacitor was prepared by synthesis of DAAQ covered CNFs. CNFs could be covered with very thin DAAQ oligomer from the results of CV, XRD, DSC, SEM images, and TEM images. Dissolved electrode active material in NMP solution has been drop-coated on carbon plate. Its electrochemical characteristics were investigated by cyclic voltammograms. And compared with different electrolyte of aqueous type. As a result, CNFs coated by DAAQ composite electrode showed relatively good electrochemical behaviors with respect to specific capacity and scan rate dependency.

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Flexible poly(vinyl alcohol)-ceramic composite separators for supercapacitor applications

  • Bon, Chris Yeajoon;Mohammed, Latifatu;Kim, Sangjun;Manasi, Mwemezi;Isheunesu, Phiri;Lee, Kwang Se;Ko, Jang Myoun
    • Journal of Industrial and Engineering Chemistry
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    • v.68
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    • pp.173-179
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    • 2018
  • Electrochemical characterization was conducted on poly(vinyl alcohol) (PVA)-ceramic composite (PVA-CC) separators for supercapacitor applications. The PVA-CC separators were fabricated by mixing various ceramic particles including aluminum oxide ($Al_2O_3$), silicon dioxide ($SiO_2$), and titanium dioxide ($TiO_2$) into a PVA aqueous solution. These ceramic particles help to create amorphous regions in the crystalline structure of the polymer matrix to increase the ionic conductivity of PVA. Supercapacitors were assembled using PVA-CC separators with symmetric activated carbon electrodes and electrochemical characterization showed enhanced specific capacitance, rate capability, cycle life, and ionic conductivity. Supercapacitors using the $PVA-TiO_2$ composite separator showed particularly good electrochemical performance with a 14.4% specific capacitance increase over supercapacitors using the bare PVA separator after 1000 cycles. With regards to safety, PVA becomes plasticized when immersed in 6 M KOH aqueous solution, thus there was no appreciable loss in tear resistance when the ceramic particles were added to PVA. Thus, the enhanced electrochemical properties can be attained without reduction in safety making the addition of ceramic nanoparticles to PVA separators a cost-effective strategy for increasing the ionic conductivity of separator materials for supercapacitor applications.

Composite Materials with MWCNTs and Conducting Polymer Nanorods and their Application as Supercapacitors

  • Liua, Lichun;Yoo, Sang-Hoon;Park, Sung-Ho
    • Journal of Electrochemical Science and Technology
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    • v.1 no.1
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    • pp.25-30
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    • 2010
  • This study demonstrated the synthesis of high-surface-area metal-free carbonaceous electrodes (CE) from anodic aluminum oxide (AAO) templates, and their application as supercapacitors. Multi-walled Carbon nanotubes (MWCNTs) were interwoven into a porous network sheet that was attached to one side of AAO template through a vacuum filtration of the homogeneously dispersed MWCNT toluene solution. Subsequently, the conducting polymer was electrochemically grown into the porous MWCNT network and nanochannels of AAO, leading to the formation of a carbonaceous metal-free film electrode with a high surface area in the given geometrical surface area. Typical conducting polymers such as polypyrrole (PPY) and poly(3,4-ethylenedioxythiophene) (PEDOT) were examined as model systems, and the resulting electrodes were investigated as supercapacitors (SCs). These SCs exhibited stable, high capacitances, with values as high as 554 F/g, 1.08 F/$cm^2$ for PPY and 237 F/g, 0.98 F/$cm^2$ for PEDOT, that were normalized by both the mass and geometric area.