• Title, Summary, Keyword: Vinylene Carbonate

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Study on the Cycling Performance of Li4Ti5O12 Electrode in the Ionic Liquid Electrolytes Containing an Additive

  • Kim, Jin-Hee;Song, Seung-Wan;Hoang, Hung-Van;Doh, Chil-Hoon;Kim, Dong-Won
    • Bulletin of the Korean Chemical Society
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    • v.32 no.1
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    • pp.105-108
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    • 2011
  • The cycling behavior of $Li_4Ti_5O_{12}$ electrode in the ionic liquid (IL)-based electrolytes containing 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide and a small amount of additive (vinylene carbonate, ethylene carbonate, fluoroethylene carbonate) was investigated. The $Li_4Ti_5O_{12}$ electrode in the IL electrolyte with an additive exhibited reversible cycling behavior with good capacity retention. Electrochemical impedance spectroscopy and FTIR studies revealed that an electrochemically stable solid electrolyte interphase was formed on the $Li_4Ti_5O_{12}$ electrode in the presence of vinylene carbonate and ethylene carbonate during cycling.

Effect of Vinylene Carbonate as an Electrolyte Additive on the Electrochemical Properties of Micro-Patterned Lithium Metal Anode (미세 패턴화된 리튬금속 전극의 Vinylene Carbonate 첨가제 도입에 따른 전기화학 특성에 관한 연구)

  • Jin, Dahee;Park, Joonam;Dzakpasu, Cyril Bubu;Yoon, Byeolhee;Ryou, Myung-Hyun;Lee, Yong Min
    • Journal of the Korean Electrochemical Society
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    • v.22 no.2
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    • pp.69-78
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    • 2019
  • Lithium metal anode with the highest theoretical capacity to replace graphite anodes are being reviewed. However, the dendrite growth during repeated oxidation/reduction reaction on lithium metal surface, which results in poor cycle performance and safety issue has hindered its successful implementation. In our previous work, we solved this problem by using surface modification technique whereby a surface pattern on lithium metal anode is introduced. Although the micro-patterned Lithium metal electrode is beneficial to control Li metal deposition efficiently, it is difficult to control the mossy-like Li granulation at high current density ($>2.0mA\;cm^{-2}$). In this study, we introduce vinylene carbonate (VC) electrolyte additive on micro patterned lithium metal anode to suppress the lithium dendrite growth. Owing to the synergetic effect of micro-patterned lithium metal anode and VC electrolyte additive, lithium dendrite at a high current density is dense. As a result, we confirmed that the cycle performance was further improved about 6 times as compared with the reference electrode.

Density Functional Studies of Ring-Opening Reactions of Li+-(ethylene carbonate) and Li+-(vinylene carbonate)

  • Han, Young-Kyu;Lee, Sang-Uck
    • Bulletin of the Korean Chemical Society
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    • v.26 no.1
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    • pp.43-46
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    • 2005
  • Reaction energies were determined for reductive ring-opening reactions of Li$^+$-coordinated ethylene carbonate (EC) and vinylene carbonate (VC) by a density functional method. We have also explored the ring-opening of Li$^+$-EC and Li$^+$-VC by reaction with a nucleophile (CH$_3$O$^-$.) thermodynamically. Our thermodynamic calculations led us to conclude that the possible reaction products are CH$_3$OCH$_2$CH$_2$OCO$_2$Li (O$_2$-C$_3$ cleavage) for Li$^+$-EC +CH$_3$O$^-$., and CH$_3$OCHCHOCO$_2$Li (O$_2$-C$_3$ cleavage) and CH$_3$OCO$_2$CHCHOLi (C$_1$-O$_2$ cleavage) for Li$^+$-VC +CH$_3$O$^-$.. The opening of VC would occur at the C$_1$-O$_2$ side by a kinetic reason, although the opening at the O$_2$-C$_3$ side is more favorable thermodynamically.

Effects of Lithium Bis(Oxalate) Borate as an Electrolyte Additive on High-Temperature Performance of Li(Ni1/3Co1/3Mn1/3)O2/Graphite Cells (LiBOB 전해액 첨가제 도입에 따른 Li(Ni1/3Co1/3Mn1/3)O2/graphite 전지의 고온특성)

  • Jeong, Jiseon;Lee, Hyewon;Lee, Hoogil;Ryou, Myung-Hyun;Lee, Yong Min
    • Journal of the Korean Electrochemical Society
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    • v.18 no.2
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    • pp.58-67
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    • 2015
  • The effects of electrolyte additives, lithium bis(oxalate)borate (LiBOB), fluoroethylene carbonate (FEC), vinylene carbonate (VC), 2-(triphenylphosphoranylidene) succinic anhydride (TPSA), on high-temperature storage properties of $Li(Ni_{1/3}Co_{1/3}Mn_{1/3})O_2$/graphite are investigated with coin-type full cells. The 1 wt.% LiBOB-containing electrolyte showed the highest capacity retention after high temperature ($60^{\circ}C$) storage for 20 days, 86.7%, which is about 5% higher than the reference electrolyte, 1.15M lithium hexafluorophosphate ($LiPF_6$) in ethylene carbonate/ethyl methyl carbonate (EC/EMC, 3/7 by volume). This enhancement is closely related to the formation of semi-carbonate compounds originated from $BOB^-$ anions, thereby resulting in lower SEI thickness and interfacial resistance after storage. In addition, the 1 wt.% LiBOB-containing electrolyte also exhibited better cycle performance at 25 and $60^{\circ}C$ than the reference electrolyte, which indicates that LiBOB is an effective additive for high-temperature performance of $Li(Ni_{1/3}Co_{1/3}Mn_{1/3})O_2$/graphite chemistry.

Suppression of Aluminum Corrosion in Lithium Bis(trifluoromethanesulfonyl)imide-based Electrolytes by the Addition of Fumed Silica

  • Louis, Hamenu;Lee, Young-Gi;Kim, Kwang Man;Cho, Won Il;Ko, Jang Myoun
    • Bulletin of the Korean Chemical Society
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    • v.34 no.6
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    • pp.1795-1799
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    • 2013
  • The corrosion property of aluminum by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is investigated in liquid and gel electrolytes consisting of ethylene carbonate/propylene carbonate/ethylmethyl carbonate/diethyl carbonate (20:5:55:20, vol %) with vinylene carbonate (2 wt %) and fluoroethylene carbonate (5 wt %) using conductivity measurement, cyclic voltammetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. All corrosion behaviors are attenuated remarkably by using three gel electrolytes containing 3 wt % of hydrophilic and hydrophobic fumed silica. The addition of silica particles contributes to the increase in the ionic conductivity of the electrolyte, indicating temporarily formed physical crosslinking among the silica particles to produce a gel state. Cyclic voltammetry also gives lower anodic current responses at higher potentials for repeating cycles, confirming further corrosion attenuation or electrochemical stability. In addition, the degree of corrosion attenuation can be affected mainly by the electrolytic constituents, not by the hydrophilicity or hydrophobicity of silica particles.

Thermal Stability of Surface Film Formed on a Graphite Negative Electrode in Lithium Secondary Batteries (리튬 이차전지의 흑연 음극에 형성된 표면피막의 열적 안정성)

  • Jeong, Soon-Ki;Lee, Ha-Na;Kim, Yang-Soo
    • Journal of the Korean Electrochemical Society
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    • v.14 no.3
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    • pp.157-162
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    • 2011
  • The stability at elevated temperatures of a surface film formed on a graphite electrode in lithium secondary batteries was investigated by transmission electron microscopy (TEM) and electrochemical AC impedance spectroscopy (EIS). TEM analysis revealed that the surface film partly dissolved in the electrolyte solution during storage at $60^{\circ}C$, resulting in a decrease in the thickness of the surface film and a change in its morphology to a porous structure. On the other hand, an increase in the impedance of the surface film which is attributable to a change in composition of the surface film was confirmed by EIS analysis during the storage at $60^{\circ}C$. It was also shown that the addition of vinylene carbonate or 1,3-propane sultone or etylene sulfite, even if limited, improves the stability of the surface film at elevated temperatures.

The Roles of Electrolyte Additives on Low-temperature Performances of Graphite Negative Electrode (전해액 첨가제가 흑연 음극의 저온특성에 미치는 영향)

  • Park, Sang-Jin;Ryu, Ji-Heon;Oh, Seung-Mo
    • Journal of the Korean Electrochemical Society
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    • v.15 no.1
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    • pp.19-26
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    • 2012
  • SEI (solid electrolyte interphase) layers are generated on a graphite negative electrode from three different electrolytes and low-temperature ($-30^{\circ}C$) charge/discharge performance of the graphite electrode is examined. The electrolytes are prepared by adding 2 wt% of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) into a standard electrolyte solution. The charge-discharge capacity of graphite electrode shows the following decreasing order; FEC-added one>standard>VC-added one. The polarization during a constant-current charging shows the reverse order. These observations illustrate that the SEI film resistance and charge transfer resistance differ according to the used additives. This feature has been confirmed by analyzing the chemical composition and thickness of three SEI layers. The SEI layer generated from the standard electrolyte is composed of polymeric carbon-oxygen species and the decomposition products ($Li_xPF_yO_z$) of lithium salt. The VC-derived surface film shows the largest resistance value even if the salt decomposition is not severe due to the presence of dense film comprising C-O species. The FEC-derived SEI layer shows the lowest resistance value as the C-O species are less populated and salt decomposition is not serious. In short, the FEC-added electrolyte generates the SEI layer of the smallest resistance to give the best low-temperature performance for the graphite negative electrode.

Characterization of SEI layer for Surface Modified Cathode of Lithium Secondary Battery Depending on Electrolyte Additives (전해질 첨가제에 따른 graphite 음극의 SEI분석 및 전기 화학적 특성 고찰)

  • Lee, Sung Jin;Cha, Eun Hee;Lim, Soo A
    • Journal of the Korean Electrochemical Society
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    • v.19 no.3
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    • pp.69-79
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    • 2016
  • Lithium ion battery with high energy density is expanding its application area to electric automobile and electricity storage field beyond existing portable electric devices. Such expansion of an application field is demanding higher characteristic and stable long life characteristic of an anode material, the natural graphite that became commercialized in lithium ion battery. This thesis produced cathode by using natural graphite anode material, analyzed creation of the cathode SEI film created due to initial reaction by using electrolyte additives, VC (vinylene carbonate), VEC (vinyl ethylene carbonate), and FEC (fluoroethylene carbonate), and considered correlation with the accompanying electrochemical transformation. This study compared and analyzed the SEI film variation of natural graphite cathode according to the electrolyte additive with SEI that is formed at the time of initial filling and cathode of $60^{\circ}C$ life characteristic. At the time of initial filling, the profile showed changes due to the SEI formation, and SEI was formed in No-Additive in approximately 0.9 V through EVS, but for VC, VEC, and FEC, the formation reaction was created above 1 V. In $60^{\circ}C$ lifespan characteristic evaluation, the initial efficiency was highest in No-Additive and showed high contents percentage, but when cycle was progressed, the capacity maintenance rate decreased more than VC and FEC as the capacity and efficiency at the time of filling decreased, and VEC showed lowest performance in efficiency and capacity maintenance rate. Changes of SEI could not be verified through SEM, but it was identified that as the cycle of SEI ingredients was progressed through FT-IR, ingredients of Alkyl carbonate ($RCO_2Li$) affiliation of the $2850-2900cm^{-1}$ was maintained more solidly and the resistance increased as cycle was progressed through EIS, and specially, it was identified that the resistance due to No-Additive and SEI of VEC became very significant. Continuous loss of additives was verified through GC-MS, and the loss of additives from partial decomposition and remodeling of SEI formed the non-uniform surface of SEI and is judged to be the increase of resistance.

Synthesis and Biological Activities of the Alternating Copolymers Containing Cyclic Ether Rings along with Carboxyl or Hydroxyl Groups on Their Backbones

  • Man Jung Han;Shin Duk Kang;Won Young Lee
    • Bulletin of the Korean Chemical Society
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    • v.11 no.2
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    • pp.154-156
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    • 1990
  • The alternating copolymers of dihydropyran(DP)-maleic anhydride(MA), dihydrofuran(DF)-MA and DF-vinylene carbonate(VC) were prepared by free radical copolymerization of DP or DF with MA or VC. The reactivity ratios for poly(DF-VC) were found to be less than unity (0.05, 0.04) and its alternating sequences were obtained by feeding an equimolar amount of the comonomers at the onset of copolymerizations. The copolymers were hydrolyzed to give poly(TP-CE), poly(TF-CE) and poly(TF-HE), whose cytotoxicities against normal and tumor cells (3LL, B16) were measured in vitro.

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Cycling Performance of Li4Ti5O12 Electrodes in Ionic Liquid-Based Gel Polymer Electrolytes

  • Kim, Jin-Hee;Kang, Yong-Ku;Kim, Dong-Won
    • Bulletin of the Korean Chemical Society
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    • v.33 no.2
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    • pp.608-612
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    • 2012
  • We investigated the cycling behavior of $Li_4Ti_5O_{12}$ electrode in a cross-linked gel polymer electrolyte based on non-flammable ionic liquid consisting of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide and vinylene carbonate. The $Li_4Ti_5O_{12}$ electrodes in ionic liquid-based gel polymer electrolytes exhibited reversible cycling behavior with good capacity retention. Cycling data and electrochemical impedance spectroscopy analyses revealed that the optimum content of the cross-linking agent necessary to ensure both acceptable initial discharge capacity and good capacity retention was about 8 wt %.