• Title, Summary, Keyword: Electrolyte Additive

Search Result 116, Processing Time 0.046 seconds

Performance of modified graphite as anode material for lithium-ion secondary battery

  • Zheng, Hua;Kim, Myung-Soo
    • Carbon letters
    • /
    • v.12 no.4
    • /
    • pp.243-248
    • /
    • 2011
  • Two different types of graphite, such as flake graphite (FG) and spherical graphite (SG), were used as anode materials for a lithium-ion secondary battery in order to investigate their electrochemical performance. The FG particles were prepared by pulverizing natural graphite with a planetary mill. The SG particles were treated by immersing them in acid solutions or mixing them with various carbon additives. With a longer milling time, the particle size of the FG decreased. Since smaller particles allow more exposure of the edge planes toward the electrolyte, it could be possible for the FG anodes with longer milling time to deliver high reversible capacity; however, their initial efficiency was found to have decreased. The initial efficiency of SG anodes with acid treatments was about 90%, showing an over 20% higher value than that of FG anodes. With acid treatment, the discharge rate capability and the initial efficiency improved slightly. The electrochemical properties of the SG anodes improved slightly with carbon additives such as acetylene black (AB), Super P, Ketjen black, and carbon nanotubes. Furthermore, the cyclability was much improved due to the effect of the conductive bridge made by carbon additives such as AB and Super P.

A Study on Photoreceptor by Using the Effect of Additives

  • Yu, Jin;Kim, Yeong Sun;Yu, Guk Hyeon
    • Bulletin of the Korean Chemical Society
    • /
    • v.22 no.7
    • /
    • pp.709-715
    • /
    • 2001
  • We have been studied photosensitization mechanism's additive effect, of perylene 3,4,9,10-tetracarboxyl-diimide and X-phthalocyanine (charge generation materials), using the photochemical and photoelectrochemical approach. It was found that the photoreceptor on the excited state reacts with metal oxide, which creates the charge transfer on the interface of SnO2/electrolyte. In the electrode (X5P1) made of five X-phthalocyanine and single perylene 3,4,9,10-tetracarboxyldiimide layers, the cathodic photocurrent of X-phthalocyanine in the 400-600 nm region was increased by the addition of perylene 3,4,9,10-tetracarboxyldiimide. The maximum wavelength of fluorescence of perylene 3,4,9,10-tetracarboxyldiimide showed no dependence on the temperature. The addition of 4-dibenzylamino-2-methylbenzaldehyde diphenylhydrazone known as charge transport material was represented as decreasing photocurrent for X-phthalocyanine and perylene 3,4,9,10-tetracarboxyldiimide, respectively. In the electrode (X1P1) made of single X-phthalocyanine and single perylene 3,4,9,10-tetracarboxyldiimide layers, an anodic photocurrent of about 10.5 nA was generated by addition of hydroquinone at 550 nm. And the characteristic of photoinduced discharge was shown to decrease by a factor of 5 and the speed of dark decay was increased by a factor of 1.2.

  • PDF

Synthesis and Characterization of Quaternary Ammonium-based Ionic Liquids Containing an Alkyl Carbonate Group

  • Nguyen, Dinh Quan;Oh, Ji-Hee;Kim, Chang-Soo;Kim, Seung-Wook;Kim, Hong-Gon;Lee, Hyun-Joo;Kim, Hoon-Sik
    • Bulletin of the Korean Chemical Society
    • /
    • v.28 no.12
    • /
    • pp.2299-2302
    • /
    • 2007
  • A series of quaternary ammonium-based ionic liquids (ILs) containing an alkyl carbonate group on the cation was first prepared and their physical and electrochemical properties including density, viscosity, thermal stability, electrochemical stability, and ionic conductivity were reported. These ILs exhibited wide electrochemical windows of at least 5.0 V and relatively high conductivities. In contrast to dialkyl-substituted ionic liquids, the ILs with an alkyl carbonate group on the cation showed much smaller drop in conductivities when mixed with a lithium salt, due to the interaction of lithium ions with carbonate groups. Upon interaction with a Li salt, the carbonyl stretching frequency of the carbonate group shifted to a lower frequency whereas the peak associated with C-O single bond moved to a higher frequency.

Improvement on Enzyme Immobilization in Polypyrrole-Glucose Oxidase Enzyme Electrode using Organic Solvent Additive I. Ultraviolet Spectroscopic Analyses (유기용매 첨가에 따른 Polypyrrole-Glucose Oxidase 효소전극의 효소고정화 향상 I. 자외선 분광분석)

  • 김현철;구할본
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.15 no.7
    • /
    • pp.615-620
    • /
    • 2002
  • In the case of immobilizing of glucose oxidase into polypyrrole (PPy) using electrosynthesis, the glucose oxidise (GOx) forms a coordinate bond with the polymers backbone. However, because of intrinsic insulation and net-chain of the enzyme, the charge transfer and mass transport are obstructed during the film growth. Therefore, the film growth is dull. We synthesized enzyme electrodes by electropolymerization added some organic solvent, such as ethanol and tetrahydrofuran (THF). The formative seeds of film growth was delayed by adding ethanol. The delay was induced by radical transfer between ethanol and pyrrole monomer. The radical transfer reactions shared the contribution of dopants between electrolyte anion and GOx polyanion. This led to increase amount of immobilized the enzyme in PPy. For the UV absorption spectra of synthetic solution before synthesis and after, in the case of ethanol added, the optical density was slightly decreased for the GOx peaks. It suggests amount of GOx in the solution was decreased and amount of GOx in the film was increased.

Improvement of Dye-Hydrogel Based Photovoltaics via Hydroquinone Electrolyte Mediators (하이드로퀴논 전해질 중간체에 의한 염료-수화젤 기반 태양전지 효율 향상)

  • KOO, HYUNG-JUN
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.27 no.5
    • /
    • pp.540-546
    • /
    • 2016
  • Besides high-efficient photovoltaics based on silicon, polymers, dye-sensitization and hybrid perovskite materials, biomimetic solar cells inspired by a leaf in nature has also been actively studied. As one example, a hydrogel based photovoltaics (HGPV) is a low-cost, environmentally friendly device and requires easy fabrication process. In this paper, the effect of hydroquinone additive on the performance of the HGPV is discussed. The photocurrent increases ~14 times upon the addition of hydroquinone into the agarose hydrogel medium. The photocurrent increase is maximum at the optimum dye concentration, while the photovoltage is barely affected by the dye concentration. The effect of the agarose content in the hydrogel and the types of dyes on the photocurrent is also investigated. Finally, it is shown that the photovoltaic performance of HGPV with hydroquinone can be drastically improved when $TiO_2$ film is deposited on the anode electrode.

Fabrication of 8YSZ-$Al_2O_3$ solid oxide full cell (SOFC) electrolyte by a spark plasma sintering method (방전 플라즈마 소결법을 이용한 8YSZ-$Al_2O_3$ 고체 산화물 연료전지 전해질 제조)

  • Kim Jae Kwang;Choi Bong Geun;Yang Jae Kyo;Choa Yong Ho;Shim Kwang Bo
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.15 no.1
    • /
    • pp.16-20
    • /
    • 2005
  • In order to improve electrical conductivity and mechanical properties of 8YSZ SOFC electrolyte material, we used Al₂O₃ as an additive and applied the spark plasma sintering (SPS) method. The sintered bodies were densified above 96 % of theoretical density at 1200℃ and possessed microstructures composed of homogeneous grains less than 1 ㎛ in size. The addition of Al₂O₃ improved fracture toughness and bending strength by inhibiting grain growth of 8YSZ and increased total ionic conductivity because grain interior conductivity appeared to remain constant and grain boundary conductivity increased. It was assumed that the dissolution of Al₂O₃ into 8YSZ which was inevitable problem at commercial sintering method was effectively prohibited by the SPS technique with a relatively low sintering temperature and the reaction between Al₂O₃ and SiO₂ present at grain boundary to produce the crystalline Al/sub 2-x/Si/sub l-y/O/sub 5/ phase, resulting in the increase of grain boundary conductivity.

High Voltage Performance of the Electrical Double Layer Capacitor with Various Electrolytes (다양한 전해액을 적용한 전기이중층 커패시터의 고전압 특성 연구)

  • Kim, Jung Wook;Choi, Seung-Hyun;Kim, Jeom-Soo
    • Journal of the Korean Electrochemical Society
    • /
    • v.20 no.2
    • /
    • pp.34-40
    • /
    • 2017
  • Electric double layer capacitors (EDLC: electric double layer capacitors) have drew attention as an energy storage device for the next generation because of their outstanding power capability and durability. But their usage is somewhat limited due to low energy density over secondary batteries. One of methods to improve the energy of EDLC is expanding the voltage window of cell operation by increasing the charge cut-off voltage. In this study, $SBP-BF_4$ (spirobipyrrolidinium tetrafluoroborate), $TEA-BF_4$ (tetraethylammonium tetraflouroborate) and $EMI-BF_4$ (1-ethyl-3-methylimidazolium tetrafluoroborate) in AN (acetonitrile) were selected to evaluate the possibility of application at high voltage environment. The LSV (linear sweep voltammetry) measurements showed that the 1.5M SBP-BF4/AN electrolyte was stable over a wide potential window and showed the best electrochemical performance compared to other combinations of electrolytes at high voltage environments (over 3.0 V). Furthermore, TMSP (tris(trimethylsilyl) phosphite) was applied to 1.5M SBP-BF4/AN in order to maintain stable performance at high voltage for the long period of time. The electrolyte with TMSP additive showed the capacity retention of 93% after 10,000 cycles at 3.3 V.

The Effect of Additional Elements on the Tailored Magnetic Properties of Electrochemically Prepared CoPtP-X Alloys (전기화학적으로 제조한 CoPtP-X합금의 첨가제 효과에 따른 맞춤형 자기적 성질)

  • Park, H.D.;Lee, K.H.;Kim, G.H.;Jeung, W.Y.;Choi, D.H.;Lee, W.Y.
    • Journal of the Korean Electrochemical Society
    • /
    • v.8 no.2
    • /
    • pp.94-98
    • /
    • 2005
  • Coptp films with the additive elements (X=Fe, Mn) of varying concentrations were prepared by in-situ electrodeposition, to tailor their magnetic properties. Alloys of CoPtP-X (X=Fe, Mn) were synthesized by changing the solution concentrations of Fe and Mn for electrodeposition. In the electrodeposited CoFePtP alloys, preferred orientation of the electrodeposited films changed from hexagonal (001) to (100) direction with increasing iron contents as revealed by X-ray diffraction, and these films exhibited various magnetic properties ranging from a typical hard magnetic to a soft magnetic property in accordance with microstructural variations. In the case of Mn addition, excellent hard magnetic property was observed at a specific Mn concentration of 0.0126 M in the electrolyte, with the coercivity of 4630 Oe and squareness of 0.856 and this was attributed to the fact that magnetization easy-axis (hexagonal c-axis) coincides with the preferred growth orientation of the film confirmed by transmission electron microscopy.

Study on the Copper Electro-refining from Copper Containing Sludge (저품위 동(Cu) 함유 슬러지로부터 동 전해정련에 관한 연구)

  • Lee, Jin-Yeon;Son, Seong Ho;Park, Sung Cheol;Jung, Yeon Jae;Kim, Yong Hwan;Han, Chul Woong;Lee, Man-seung;Lee, Ki-Woong
    • Resources Recycling
    • /
    • v.26 no.6
    • /
    • pp.84-90
    • /
    • 2017
  • The electro-refining process was performed to recovery high purity copper from low grade copper containing sludge in sulfuric acid. The surface morphologies and roughness of electro-refining copper were analyzed with variation of the type and concentration of organic additives, the best surface morphology was obtained 5 ppm of the gelatin type and 5 to 10 ppm of the thiol type organic additive. The crude metal consisted of copper with 86.635, 94.969 and 99.917 wt.%, several impurity metals of iron, nickel, cobalt and tin by pyro-metallurgical process. After electro-refining process, the purity of copper increases to 3N or 4N grade. The impurity concentrations and copper purities of copper crude metals, electrolyte and electro-refining copper were analyzed using ICP-OES, the electro-refining time and purity of copper crude metal to recover 4N grade copper were deduced.

Electrodeposition of $^{237}Np$ for Alpha Spectrometry and Application to Spent Nuclear Fuel Samples (알파분광분석법에 의한 $^{237}Np$ 정량 및 사용후핵연료 시료에의 적용)

  • Joe Kih-Soo;Kim Jung-Suck;Han Sun-Ho;Park Yeong-Jai;Kim Won-Ho
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.4 no.2
    • /
    • pp.95-102
    • /
    • 2006
  • Alpha spectrometry was studied for the determination of $^{237}Np$ in spent nuclear fuel samples. The optimum condition for the electrodeposition of $^{237}Np$ was obtained as follows : for $1{\sim}1.5$ hour of deposition time, at the current intensity of $1.2{\sim}1.5$ A and at sodium sulfate electrolyte without organic additive. The deposition yield and its reproducibility on $^{237}Np$ was decreased as the amount of $^{237}Np$ decreased from 4.16 Bq down to 0.0264 Bq(1ng). The recovery yield of $^{237}Np$ determined by alpha spectrometry after separation in synthetic solution was $98.8{\pm}5.1%$(n=4). The contents of $^{237}Np$ in spent nuclear fuel samples were determined and the result showed an agreement within 10% of a difference between the measurement and the calculation.

  • PDF