• 제목, 요약, 키워드: Electrolyte Additive

검색결과 116건 처리시간 0.027초

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

  • 신원경;박세미;김동원
    • 전기화학회지
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    • v.17 no.3
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    • pp.156-163
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    • 2014
  • 본 연구에서는 불소계 실란을 첨가제로 사용하여 전해액의 열화 반응을 억제함으로써 리튬이온전지의 싸이클 특성을 향상시키고자 하였다. 첨가제로 사용된 trifluoropropyltrimethoxysilane은 리튬염과 카보네이트계 유기 용매로 이루어진 액체 전해질보다 전기화학적 산화, 환원 분해반응이 먼저 일어나 음극 및 양극 표면에서 안정적인 고체전해질계면 (solid electrolyte interphase, SEI) 막을 형성하며, 5 wt.%의 첨가제를 포함하는 경우 가장 우수한 전기화학적 특성을 나타내었다. SEM 및 XPS 분석을 통해 전극 표면에 생성된 피막의 화학 성분을 분석하였으며, 이들 결과로부터 새로운 SEI 형성 첨가제로서 불소계 실란의 가능성을 확인하였다.

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

  • 유선경;박수길
    • 전기화학회지
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    • v.20 no.1
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    • pp.13-17
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    • 2017
  • 본 연구에서는 고전압용 전기화학 커패시터에 응용을 위한 유기 전해액 개발에 관한 연구를 실시하였다. 사용한 기준 전해액으로는 1M의 $SBPBF_4$염이 포함된 EC:DMC(1:1) 복합 전해액을 사용하였으며, 고전압 안정성을 위해 기준 전해액에 첨가제 GBL을 5 wt.% 첨가했다. 0-3.5 V 전압 범위에서 초기 250 사이클까지의 효율이 약 2.5배 향상된 것을 확인할 수 있었으며, 2000 사이클 이후에는 약 3배 이상의 커패시턴스 효율이 유지되는 것을 확인하였다. 고전압에서 GBL이 전해액 보다 먼저 분해를 일으켜 전해액이 분해되는 현상을 억제하며 안정성을 향상시키는 효과가 있는 것으로 판단된다. 또한 분해된 GBL이 전극 표면에 흡착하여 안정한 SEI 층을 형성해줌으로서, 전극 표면을 보호하여 전해질과의 부반응을 억제해주는 역할을 하는 것으로 판단된다.

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

  • 권용갑;최호석;이중기
    • 전기화학회지
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    • v.15 no.3
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    • pp.190-197
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    • 2012
  • 비닐에틸렌 카보네이트(VEC: vinyl ethylene carbonate)를 전해질 첨가제로 사용했을 때 하이브리드 커패시터(hybrid capacitors) 전극에서 나타나는 전기화학적 특성변화에 대해서 고찰하였다. 하이브리드 커패시터는 양극은 활성탄(AC : activated carbon) 음극은 리튬티타늄옥사이드(LTO: $Li_4Ti_5O_{12}$)를 사용하였고, 전해질로서는 에틸렌 카보네이트(EC: ethylene carbonate): 디메틸 카보네이트 (DMC: dimethyl carbonate) : 에틸메틸 카보네이트(EMC : ethyl methyl carbonate)를 사용하였고, 염으로 육불화인산리튬($LiPF_6$: lithium hexafluoro phosphate)을 사용하였다. 전극 표면의 산소관능기 그룹을 제거하고, 표면을 환원시킴으로써 전극에 안정성을 향상시킨다고 알려진 VEC의 첨가량에 따른 전기화학적 특성을 평가하였으며, 0.7%(부피비)의 VEC첨가시, 가장 우수한 전기화학적 특성을 얻을 수 있었다. 0.7% 이상 첨가하였을 경우, 오히려 부반응 증가로 전기화학적 성능이 감소하였다. X-ray photoelectron spectrocopy (XPS) 결과로부터 LTO 전극에서 VEC가 첨가되지 않은 전해질에 비해 LiF가 감소한 것을 확인 할 수 있었다. VEC가 첨가되지 않은 전해질은 2500 사이클 후, 43.2 %의 용량 유지를 나타냈지만, 최적화된 VEC 첨가를 통하여 82.7 %의 높은 용량을 유지하는 특성을 가진 하이브리드 커패시터를 얻을 수 있었다.

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.