• Title, Summary, Keyword: Electrolyte Additive

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Triphenyl phosphate as an Efficient Electrolyte Additive for Ni-rich NCM Cathode Materials

  • Jung, Kwangeun;Oh, Si Hyoung;Yim, Taeeun
    • Journal of Electrochemical Science and Technology
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    • v.12 no.1
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    • pp.67-73
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    • 2021
  • Nickel-rich lithium nickel-cobalt-manganese oxides (NCM) are viewed as promising cathode materials for lithium-ion batteries (LIBs); however, their poor cycling performance at high temperature is a critical hurdle preventing expansion of their applications. We propose the use of a functional electrolyte additive, triphenyl phosphate (TPPa), which can form an effective cathode-electrolyte interphase (CEI) layer on the surface of Ni-rich NCM cathode material by electrochemical reactions. Linear sweep voltammetry confirms that the TPPa additive is electrochemically oxidized at around 4.83 V (vs. Li/Li+) and it participates in the formation of a CEI layer on the surface of NCM811 cathode material. During high temperature cycling, TPPa greatly improves the cycling performance of NCM811 cathode material, as a cell cycled with TPPa-containing electrolyte exhibits a retention (133.7 mA h g-1) of 63.5%, while a cell cycled with standard electrolyte shows poor cycling retention (51.3%, 108.3 mA h g-1). Further systematic analyses on recovered NCM811 cathodes demonstrate the effectiveness of the TPPa-based CEI layer in the cell, as electrolyte decomposition is suppressed in the cell cycled with TPPa-containing electrolyte. This confirms that TPPa is effective at increasing the surface stability of NCM811 cathode material because the TPPa-initiated POx-based CEI layer prevents electrolyte decomposition in the cell even at high temperatures.

Benzotriazole as an electrolyte additive on lithium-ion batteries performance

  • Hamenu, Louis;Madzvamuse, Alfred;Mohammed, Latifatu;Lee, Yong Min;Ko, Jang Myoun;Bon, Chris Yeajoon;Kim, Sang Jun;Cho, Won Il;Baek, Yong Gu;Park, Jongwook
    • Journal of Industrial and Engineering Chemistry
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    • v.53
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    • pp.241-246
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    • 2017
  • Liquid electrolyte consisting of 1 M LiPF6 in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 0.1 wt% benzotriazole (BzTz) is studied in $LiCoO_2$//graphite battery system at room temperature. Benzotriazole addition introduces excellent electrochemical stability (5.6 V vs Li) and good ionic conductivity properties at room temperature. Also, this electrolyte shows good cycling performance and better discharge capacities at high C-rates relative to the pristine electrolyte. Furthermore, the additive allows the formation of a good solid electrolyte interphase (SEI) per cyclic voltammetry (CV) examination. These specialized properties make this liquid electrolyte ideal for high power and high voltage applications.

Silyl-group functionalized organic additive for high voltage Ni-rich cathode material

  • Jang, Seol Heui;Jung, Kwangeun;Yim, Taeeun
    • Current Applied Physics
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    • v.18 no.11
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    • pp.1345-1351
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    • 2018
  • To allow stable cycling of layered nickel-rich cathode material at high voltage, silyl-functionalized dimethoxydimethylsilane is proposed as a multi-functional additive. In contrast to typical functional additive, dimethoxydimethylsilane does not make artificial cathode-electrolyte interfaces by electrochemical oxidation because it is quite stable under anodic polarization. We find that dimethoxydimethylsilane mainly focuses on scavenging nucleophilic fluoride species that can be produced by electrolyte decomposition during cycling, leading to improving interfacial stability of both nickel-rich cathode and graphite anode. As a result, the cell cycled with dimethoxydimethylsilane-controlled electrolyte exhibits 65.7% of retention after 100 cycle, which is identified by systematic spectroscopic analyses for the cycled cell.

Enhancement of Electrolyte Properties for High Energy Density Supercapacitors by using Additive Materials

  • Kim, Cheong;Habazaki, Hiroki;Park, Soo Gil
    • Journal of Electrochemical Science and Technology
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    • v.7 no.3
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    • pp.214-217
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    • 2016
  • In this study, we studied the enhancement of the energy densities of electrochemical capacitors by improving the working voltage range of the electrolyte. To prevent the decomposition of the electrolyte, stable SEI layers were formed by reductive degradation of additive materials such as fluoro-ethylene carbonate (FEC) and vinyl ethylene carbonate (VEC) before degradation of the base electrolyte. As a result, the solution resistance (Rs) of EC:DMC + SL 20 % + VEC 1 % electrolytes observed 1.47 Ω and the charge transfer resistance (Rct) was 2.64 Ω at the open circuit voltage. Additionally, a cycle retention of 94 % was observed for EC:DMC + SL 20 % + VEC 1 % after 500 cycles at 3.5 V.

Trifluoropropyltrimethoxysilane as an Electrolyte Additive to Enhance the Cycling Performances of Lithium-Ion Cells (Trifluoropropyltrimethoxysilane 전해질 첨가제를 이용한 리튬이온전지의 싸이클 특성 향상)

  • Shin, Won-Kyung;Park, Se-Mi;Kim, Dong-Won
    • Journal of the Korean Electrochemical Society
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    • v.17 no.3
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    • pp.156-163
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    • 2014
  • In this study, we tried to improve the cycling performance of lithium-ion batteries by suppressing decomposition of the electrolyte solution containing fluorsilane-based additive. Trifluoropropyltrimethoxysilane was electrochemically oxidized and reduced prior to the decomposition of the liquid electrolyte composed of lithium salt and carbonate-based organic solvent. Thus, the stable solid electrolyte interphase (SEI) layer on both negative electrode and positive electrode was formed, and it was confirmed that the cycling performance of lithium-ion batteries assembled with electrolyte solution containing 5 wt.% trifluoropropyltrimethoxysilane was the mostly enhanced. The products formed on electrodes were analyzed by the SEM and XPS analysis, and it was demonstrated that trifluoropropyltrimethoxysilane can be one of the promising SEI-forming additives.

Organic Electrolyte of the Additive the Gamma-Butyroloctone (GBL) for Additive Material Application to High Voltage Electrochemical Capacitor (Gamma-butyroloctone(GBL)을 첨가한 유기계 전해액의 고전압용 전기화학 커패시터로의 응용)

  • You, Sun-Kyung;Park, Soo-Gil
    • Journal of the Korean Electrochemical Society
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    • v.20 no.1
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    • pp.13-17
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    • 2017
  • In this study, we studied the organic electrolyte application to electrochemical capacitor for high operation voltage. For high operating voltage, 5 wt % of gamma butyroloctone (GBL) was added in the bare electrolyte. During the cycle performance, stable SEI layers were formed by reductive decomposition of additive GBL. As a result, columbic efficient of 1M $SBPBF_4$ in EC:DMC(1:1) with GBL composite was enhanced to 70% after the 2000th cycle at voltage range 0-3.5 V. Additionally, SEI layer protected the surface of electrode and prevent the side-reaction between electrolyte to electrode.

Effect of Vinyl Ethylene Carbonate on Electrochemical Characteristics for Activated Carbon/Li4Ti5O12 Capacitors (활성탄/리튬티탄산화물 커패시터의 전기화학적 특성에 미치는 비닐에틸렌카보네이트의 영향)

  • Kwon, Yong-Kab;Choi, Ho-Suk;Lee, Joong-Kee
    • Journal of the Korean Electrochemical Society
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    • v.15 no.3
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    • pp.190-197
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    • 2012
  • We employed the vinyl ethylene carbonate (VEC) as an electrolyte additive and investigated the effect of the electrolyte additive on the electrochemical performance in hybrid capacitor. The activated carbon was adopted as cathode material, and the $Li_4Ti_5O_{12}$ oxide was used as anode material. The electrolyte was prepared with the $LiPF_6$ salt in the mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate(EMC). We evaluated the electrochemical performance of the hybrid capacitor with increasing the amount of the VEC electrolyte additive, which is known as the remover of oxygen functional group and the stabilizer of the electrode by reducing the surface of electrode, and obtained the superior performance data especially at the addition of the VEC electrolyte additive of around 0.7 vol%. On the contrary, the addition of the VEC more than 0.7 vol% in the electrolyte leads to the degradation in electrochemical performance of hybrid capacitor, suggesting the increase of the side reaction from the excessive VEC additive. X-ray photoelectron spectroscopy (XPS) revealed that the addition of the VEC suppressed the formation of LiF component, which is known as the insulator, on the surface of electrode. The optimized addition of VEC exhibited the improved capacity retention around 82.7% whereas the bare capacitors without VEC additive showed the 43.2% of capacity retention after 2500 cycling test.

Influence of ionic liquid additives on the conducting and interfacial properties of organic solvent-based electrolytes against an activated carbon electrode

  • Kim, Kyungmin;Jung, Yongju;Kim, Seok
    • Carbon letters
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    • v.15 no.3
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    • pp.187-191
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    • 2014
  • This study reports on the influence of N-butyl-N-methylpyrrolidinium tetrafluoroborate ($PYR_{14}BF_4$) ionic liquid additive on the conducting and interfacial properties of organic solvent based electrolytes against a carbon electrode. We used the mixture of ethylene carbonate/dimethoxyethane (1:1) as an organic solvent electrolyte and tetraethylammonium tetrafluoroborate ($TEABF_4$) as a common salt. Using the $PYR_{14}BF$ ionic liquid as additive produced higher ionic conductivity in the electrolyte and lower interface resistance between carbon and electrolyte, resulting in improved capacitance. The chemical and electrochemical stability of the electrolyte was measured by ionic conductivity meter and linear sweep voltammetry. The electrochemical analysis between electrolyte and carbon electrode was examined by cyclic voltammetry and electrochemical impedance spectroscopy.

Study on the Cycling Performances of Lithium-Ion Polymer Cells Containing Polymerizable Additives

  • Kim, Dong-Won
    • Bulletin of the Korean Chemical Society
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    • v.30 no.2
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    • pp.319-322
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    • 2009
  • Gel polymer electrolytes were prepared by immersing a porous poly(vinylidene fluoride-co-hexafluoropropylene) membrane in an electrolyte solution containing small amounts of polymerizable additive (3,4-ethylenedioxythiophene, thiophene, biphenyl). The organic additives were electrochemically oxidized to form conductive polymer films on the electrode at high potential. With the gel polymer electrolytes containing different organic additive, lithium-ion polymer cells composed of carbon anode and LiCo$O_2$ cathode were assembled and their cycling performances were evaluated. Adding small amounts of thiophene or 3,4-ethylenedioxythiophene to the gel polymer electrolyte was found to reduce the charge transfer resistance in the cell and it thus exhibited less capacity fading and better high rate performance.

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.