• Title, Summary, Keyword: Electrochemical Performance

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A New Way to Prepare MoO3/C as Anode of Lithium ion Battery for Enhancing the Electrochemical Performance at Room Temperature

  • Yu, Zhian;Jiang, Hongying;Gu, Dawei;Li, Jishu;Wang, Lei;Shen, Linjiang
    • Journal of Electrochemical Science and Technology
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    • v.7 no.2
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    • pp.170-178
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    • 2016
  • Composited molybdenum oxide and amorphous carbon (MoO3/C) as anode material for lithium ion batteries has been successfully synthesized by calcining polyaniline (PANI) doped with ammonium heptamolybdate tetrahydrate (AMo). The as prepared electrode material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The electrochemical performance of the anode was investigated by galvanostatic charge/discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The MoO3/C shows higher specific capacity, better cyclic performance and rate performance than pristine MoO3 at room temperature. The electrochemical of MoO3/C properties at various temperatures were also investigated. At elevated temperature, MoO3/C exhibited higher specific capacity but suffered rapidly declines. While at low temperature, the electrochemical performance was mainly limited by the low kinetics of lithium ion diffusion and the high charge transfer resistance.

Electroactive Conjugated Polymer / Magnetic Functional Reduced Graphene Oxide for Highly Capacitive Pseudocapacitors: Electrosynthesis, Physioelectrochemical and DFT Investigation

  • Ehsani, A.;Safari, R.;Yazdanpanah, H.;Kowsari, E.;Shiri, H. Mohammad
    • Journal of Electrochemical Science and Technology
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    • v.9 no.4
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    • pp.301-307
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    • 2018
  • The current study fabricated magnetic functional reduced graphene oxide (MFRGO) by relying on ${FeCl_4}^-$ magnetic anion confined to cationic 1-methyl imidazolium. Furthermore, for improving the electrochemical performance of conductive polymer, hybrid poly ortho aminophenol (POAP)/ MFRGO films have then been fabricated by POAP electropolymerization in the presence of MFRGO nanorods as active electrodes for electrochemical supercapacitors. Surface and electrochemical analyses have been used for characterization of MFRGO and POAP/ MFRGO composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. Prepared composite film exhibited a significantly high specific capacity, high rate capability and excellent cycling stability (capacitance retention of ~91% even after 1000 cycles). These results suggest that electrosynthesized composite films are a promising electrode material for energy storage applications in high-performance pseudocapacitors.

Characterization and Electrochemical Performance of Composite BSCF Cathode for Intermediate-temperature Solid Oxide Fuel Cell

  • Kim, Yu-Mi;Kim-Lohsoontorn, Pattaraporn;Bae, Joong-Myeon
    • Journal of Electrochemical Science and Technology
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    • v.2 no.1
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    • pp.32-38
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    • 2011
  • The composite barium strontium cobalt ferrite (BSCF) cathodes were investigated in the intermediate temperature range of solid oxide fuel cells (SOFCs). The characteristics and electrochemical performances of composited BSCF/samarium doped ceria (SDC); BSCF/gadolinium doped ceria (GDC); and BSCF/SDC/GDC were compared to single BSCF cathode. The BSCF used in this study were synthesized using glycine nitrate process and mechanically mixing was used to fabricate a composite cathode. Using a composite form, the thermal expansion coefficient (TEC) could be reduced and BSCF/SDC/GDC exhibited the lowest TEC value at $18.95{\times}10^{-6}K^{-1}$. The electrochemical performance from half cells and single cells exhibited nearly the same trend. All the composite cathodes gave higher electrochemical performance than the single BSCF cathode (0.22 $Wcm^{-2}$); however, when two kinds of electrolyte were used (BSCF/SDC/GDC, 0.36$Wcm^{-2}$), the electrochemical performance was lower than when the BSCF/SDC (0.45 $Wcm^{-2}$) or BSCF/GDC (0.45 $Wcm^{-2}$) was applied as cathode ($650^{\circ}C$, 97%$H_2$/3%$H_2O$ to the anode and ambient air to the cathode).

Influence of carbon black on electrochemical performance of graphene-based electrode for supercapacitor (슈퍼커패시터를 위한 그래핀 기반 전극의 전기화학적 특성에 대한 카본블랙 도입의 효과)

  • Kim, Ki-Seok;Park, Soo-Jin
    • 한국신재생에너지학회:학술대회논문집
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    • pp.95.1-95.1
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    • 2011
  • In this work, graphene was prepared by modified Hummers method and prepared graphene was applied to electrode materials for supercapacitor. In addition, to enhance the electrochemical performance of graphene, carbon black was deposited onto graphene via chemical reduction. The effect of the carbon black content incorporated on the electrochemical properties of the graphene-based electrodes was investigated. It was found that nano-scaled carbon black aggregates were deposited and dispersed onto the graphene by the chemical reduction of acid treated carbon black and graphite oxide. From the cyclic voltammograms, carbon black-deposited graphene (CB-GR) showed improved electrochemical performance, i.e., current density, quicker response, and better specific capacitance than that of pristine graphene. This indicates that the carbon black deposited onto graphene served as an conductive materials between graphene layers, leading to reducing the contact resistance of graphene and resulted in the increase of the charge transfer between graphene layers by bridge effect.

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Effects of the Mixing of an Active Material and a Conductive Additive on the Electric Double Layer Capacitor Performance in Organic Electrolyte

  • Yang, Inchan;Kwon, Soon Hyung;Kim, Bum-Soo;Kim, Sang-Gil;Lee, Byung-Jun;Kim, Myung-Soo;Jung, Ji Chul
    • Korean Journal of Materials Research
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    • v.25 no.3
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    • pp.132-137
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    • 2015
  • The effects of the mixing of an active material and a conductive additive on the electrochemical performance of an electric double layer capacitor (EDLC) electrode were investigated. Coin-type EDLC cells with an organic electrolyte were fabricated using the electrode samples with different ball-milling times for the mixing of an active material and a conductive additive. The ball-milling time had a strong influence on the electrochemical performance of the EDLC electrode. The homogeneous mixing of the active material and the conductive additive by ball-milling was very important to obtain an efficient EDLC electrode. However, an EDLC electrode with an excessive ball-milling time displayed low electrical conductivity due to the characteristic change of a conductive additive, leading to poor electrochemical performance. The mixing of an active material and a conductive additive played a crucial role in determining the electrochemical performance of EDLC electrode. The optimal ball-milling time contributed to a homogeneous mixing of an active material and a conductive additive, leading to good electrochemical performance of the EDLC electrode.

Study on Electrochemical Performance of Solid-State-Electrode on Steel bar in Chloride Solution (염화물 수용액 중의 철근에 대한 고체전극의 전기화학적 성능 연구)

  • Park, Dong-Jin;Park, Jang-Hyun;Lee, Han-Seung;Subbiah, Karthick
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.147-148
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    • 2018
  • In order to compare the electrochemical performance with that of Calomel Electrode, MnO2 solid-state-electrode was fabricated and its potential and impedance were measured in chloride aqueous solution. As a result, the SCPS without chloride ions showed a potential of -200 mV or more and an impedance over 2000 Ωcm, but the potential below -600 mV and the impedance below -200 Ωcm showed as the chloride concentration in the solution increased. It is considered electrochemical studies on the corrosion of rebar are necessary for the MOE, which shows the same tendency as SCE and exhibits electrochemical performance, over the Mortar level in the future.

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Effect of Electrochemical Reduction of Ruthenium Black Cathode Catalyst on the Performance of Polymer Electrolyte Membrane Fuel Cells (캐소드 루테늄 촉매의 전기화학적 환원 처리가 고분자 전해질 연료전지 성능에 미치는 영향)

  • Choi, Jong-Ho
    • Journal of the Korean Electrochemical Society
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    • v.14 no.2
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    • pp.110-116
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    • 2011
  • Ru black was used for cathode catalyst in polymer electrolyte membrane fuel cell which showed low performance at the initial test. However, it was observed that the performance of Ru black cathode was dramatically enhanced after certain kind of experiment compared with initial one. It might be due to an electrochemical treatment in which a voltage was applied to the Ru cathode for constant period time. When a constant potential of 0.1 V was applied to Ru cathode for 30 min, the fuel cell performance of Ru cathode showed the best results. In order to investigate the effect of electrochemical treatment on the performance enhancement, the characteristics of electrochemically treated Ru black was compared with that of Ru black which was reduced under $H_2$ atmosphere. From XRD results, it was turned out that Ru black was not completely converted to metallic Ru by electrochemical treatment, but it is sufficient to be one of reasons for the performance enhancement. According to the results of CO stripping voltammetry, it was observed that some Ru was removed from Ru electrode by electrochemical treatment which might have a bad effect on the fuel cell performance. The removal of some Ru from as-received Ru black by electrochemical treatment is also another reason for the enhancement of fuel cell performance.

Synthesis of Mesostructured Conducting Polymer-Carbon Nanocomposites and Their Electrochemical Performance

  • Choi, Moon-Jung;Lim, Byung-Kwon;Jang, Jyong-Sik
    • Macromolecular Research
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    • v.16 no.3
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    • pp.200-203
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    • 2008
  • A conducting polymer layer was introduced into the pore surface of mesoporous carbon via vapor infiltration of a monomer and subsequent chemical oxidative polymerization. The polypyrrole, conducting polymer has attracted considerable attention due to the high electrical conductivity and stability under ambient conditions. The mesoporous carbon-polypyrrole nanocomposite exhibited the retained porous structure, such as mesoporous carbon with a three-dimensionally connected pore system after intercalation of the polypyrrole layer. In addition, the controllable addition of pyrrole monomer can provide the mesoporous carbon-polypyrrole nanocomposites with a tunable amount of polypyrrole and texture property. The polypyrrole layer improved the electrode performance in the electrochemical double layer capacitor. This improved electrochemical performance was attributed to the high surface area, open pore system with three-dimensionally interconnected mesopores, and reversible redox behavior of the conducting polypyrrole. Furthermore, the correlation between the amount of polypyrrole and capacitance was investigated to check the effect of the polypyrrole layer on the electrochemical performance.

Electrochemical Performance of AlF3-Coated LiV3O8 for Aqueous Rechargeable Lithium Ion Batteries

  • Tron, Artur;Kang, Hyunchul;Kim, Jinho;Mun, Junyoung
    • Journal of Electrochemical Science and Technology
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    • v.9 no.1
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    • pp.60-68
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    • 2018
  • In aqueous rechargeable lithium ion batteries, $LiV_3O_8$ exhibits obviously enhanced electrochemical performance after $AlF_3$ surface modification owing to improved surface stability to fragile aqueous electrolyte. The cycle life of $LiV_3O_8$ is significantly enhanced by the presence of an $AlF_3$ coating at an optimal content of 1 wt.%. The results of powder X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, and galvanostatic charge-discharge measurements confirm that the electrochemical improvement can be attributed mainly to the presence of $AlF_3$ on the surface of $LiV_3O_8$. Furthermore, the $AlF_3$ coating significantly reduces vanadium ion dissolution and surface failure by stabilizing the surface of the $LiV_3O_8$ in an aqueous electrolyte solution. The results suggest that the $AlF_3$ coating can prevent the formation of unfavorable side reaction components and facilitate lithium ion diffusion, leading to reduced surface resistance and improved surface stability compared to bare $LiV_3O_8$ and affording enhanced electrochemical performance in aqueous electrolyte solutions.