• 제목/요약/키워드: Polymer cathode

검색결과 237건 처리시간 0.026초

Yttrium-doped and Conductive Polymer-Coated High Nickel Layered Cathode Material with Enhanced Structural Stability

  • Shin, Ji-Woong;Lee, Seon-Jin;Nam, Yun-Chae;Son, Jong-Tae
    • Journal of Electrochemical Science and Technology
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    • 제12권2호
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    • pp.272-278
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    • 2021
  • In this study, high nickel layered LiNi0.8Co0.1Mn0.1O2 cathode materials for lithium-ion batteries were modified by yttrium doping and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) coating. The effects of yttrium doping and PEDOT:PSS coating on the structural and electrochemical properties of the LiNi0.8Co0.1Mn0.1O2 cathode material were investigated and compared. The substitution of nickel with an electrochemically inert yttrium was confirmed to be successful in stabilizing the layered structure framework. Moreover, coating the surfaces of the LiNi0.8Co0.1Mn0.1O2 particles with a conductive polymer, PEDOT:PSS, improved the capacity retention, thermal stability, and impedance of the cathode material by increasing its ionic and electric conductivities.

Synthesis of a New Cathode Redox Polymer for High Performance in Biofuel Cells

  • Choi, Young-Bong;Lee, Jung-Min;Kim, Hyug-Han
    • Bulletin of the Korean Chemical Society
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    • 제35권9호
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    • pp.2803-2808
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    • 2014
  • High potential and fast electron transfer of a cathode mediator are significant factors for improving the performance of biofuel cells. This paper reports the first synthesis of a cathode redox polymer that is a coordination complex of poly (acrylic acid-vinylpyridine-acryl amide) (PAA-PVP-PAA) and [Os(4,4'-dicarboxylic acid-2,2'-bipyridine)$_2Cl_2]^{/+}$ ($E^{\circ}=0.48V$ versus Ag/AgCl). Bilirubin oxidase can be easily incorporated into this polymer matrix, which carried out the four-electron oxygen under typical physiological conditions (pH 7.2, 0.14 M NaCl, and $37^{\circ}C$). This new polymer showed an approximately 0.1 V higher redox potential than existing cathode mediators such as PAA-PVI-$[Os(dCl-bpy)_2Cl]^{+/2+}$. In addition, we suggest increasing the polymer solubility with two hydrophilic groups present in the polymer skeleton to further improve fast electron transfer within the active sites of the enzyme. The maximum power density achieved was 60% higher than that of PAA-PVI-$[Os(dCl-bpy)_2Cl]^{+/2+}$. Furthermore, high current density and electrode stability were confirmed for this osmium polymer, which makes it a promising candidate for high-efficiency biofuel cells.

ZnO를 대체 가능한 새로운 Viologen 유도체가 적용된 역구조 고분자 태양전지 (ZnO-free Inverted Polymer Solar Cells Based on New Viologen Derivative as a Cathode Buffer Layer)

  • 김윤환;김동근;김주현
    • 공업화학
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    • 제27권5호
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    • pp.512-515
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    • 2016
  • 새로운 viologen 유도체인 1,1'-bis(3,4-dihydroxybutyl)-[4,4'-bipyridine]-1,1'-diium bromide (V-Pr-2OH)을 합성하여 PTB7 : $PC_{71}BM$ Blend를 기반으로 하는 inverted polymer solar cells (iPSCs)에 cathode buffer layer로 적용하였다. V-Pr-2OH이 cathode buffer layer로 적용된 PSCs (ITO/V-Pr-2OH/PTB7 : $PC_{71}BM/MoO_3/Ag$)의 power conversion efficiency (PCE)는 7.28%이었다. V-Pr-2OH이 없는 iPSCs (ITO/ZnO/PTB7 : $PC_{71}BM/MoO_3/Ag$)의 PCE (7.41%)에 상응하는 값이다. 그러므로 본 연구에서는 높은 열처리 공정이 필요한 ZnO가 배제된, 즉 높은 온도의 열처리 없이도 제작 가능한 PSC에 대한 가능성을 보여주고 있다.

리튬 폴리머 전지 $LiFePO_4$의 전기화학적 특성 (Electrochamical Properties of $LiFePO_4$ Electrodes for Lithium Polymer Battery)

  • 공명철;구할본
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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    • pp.5-9
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    • 2005
  • $LiFePO_4$ is a potential candidate for the cathode material of the lithium polymer batteries. $LiFePO_4$ cathode active materials were synthesized by coating on the $LiFePO_4$ was tried using $TiO_2$ and corbon in oreder to increase cyclic performance and electronic conductivity. Highly dispersed on the particles enhances the electronic conductivity and increases the capacity. For lithium polymer battery applications, $LiFePO_4$/SPE/Li and $LiFePO_4$-$TiO_2$/SPE/Li 'cells were characterized electrochemically by cyclic volatammetry and charge/discharge cycling. The $LiFePO_4$-carbon-$TiO_2$ cathode in PVDF-PC-EC-$LiCIO_4$ electrolyte showed high capacity at high current density.

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Designing of a Novel Core-Shell-Structured Co-free Cathode Material with Enhanced Thermal and Structural Stability for Lithium Ion Batteries

  • Shin, Ji-Woong;Nam, Yun-Chae;Son, Jong-Tae
    • 전기화학회지
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    • 제22권4호
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    • pp.172-176
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    • 2019
  • The first commercialized cathode material, $LiCoO_2$, suffers from disadvantages such as high cost and toxicity and also possesses safety problems. The nickel-rich $LiNi_{0.9}Mn_{0.1}O_2$ cathode material, used as an alternative to $LiCoO_2$, has highly reversible capacity and high energy density. So, the nickel-rich $LiNi_{0.9}Mn_{0.1}O_2$ cathode material is widely used as an alternative to $LiCoO_2$ due to its highly reversible capacity and high energy density. However, $LiNi_{0.9}Mn_{0.1}O_2$ has several disadvantages as well, such as poor cycle performance and poor thermal instability. To address these problems, we synthesized a new material, $LiNi_{0.5}Mn_{0.5}O_2$, as a shell on the surface of a core to suppress the surface degradation. The new material showed high structural and thermal stabilities and could also maintain a high capacity. The capacity retention of the core-shell cathode (87.7%) was better than that of the core cathode (76.9%) after 50 cycles. Analysis using differential scanning calorimetry revealed that the heat generation in the core-shell cathode ($65.9Jg^{-1}$) was lower than that in the core cathode ($559.7Jg^{-1}$).

리튬 폴리머 전지용 $LiMnO_2$정극의 도전재에 따른 전기 화학적 특성 (Electrochemical Properties of $LiMnO_2$ Cathode as a Function of Addition of Electric Active Materials for Lithium Polymer Batteries)

  • 조영재;김종욱;구할본
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2001년도 하계학술대회 논문집
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    • pp.474-477
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    • 2001
  • The properties of LiMnO$_2$ was studied as a cathode active material for lithium polymer batteries. LiMnO$_2$ cathode active materials were synthesized by the reaction of LiOH . $H_2O$ and Mn$_2$O$_3$at various temperature under argon atmosphere. For lithium polymer battery applications, the LiMnO$_2$cell was characterized electrochemically by charge-discharge experiments and a.c. impedance spectroscopy. And the relationship between the characteristics of powders and electrochemical properties was studied in this research. A maximum discharge capacity of 160-170 mAh/g for ο-LiMnO$_2$ cell was achieved. Used that SP270 as electric active material in LiMnO$_2$, it is excellent than property of electric active material used Acetylene black or KS6 at charge/discharge capacity.

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리튬폴리머전지용 정극활물질 LiFePO4의 전기화학적 특성 (Electrochemical Properties of LiFePO4 Cathode Materials for Lithium Polymer Batteries)

  • 공명철;김현수;구할본
    • 한국전기전자재료학회논문지
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    • 제19권6호
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    • pp.519-523
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    • 2006
  • $LiFePO_4$ has been received attention as a potential cathode material for the lithium secondary batteries. In our study, $LiFePO_4$ cathode active materials were synthesized by a solid-state reaction. It was modified by coating $TiO_2$ and carbon in order to enhance cyclic performance and electronic conductivity. $TiO_2$ and carbon coatings on $LiFePO_4$ materials enhanced the electronic conductivity and its charge/discharge capacity. For lithium polymer battery applications, $LiFePO_4$/solid polymer electrolyte (SPE)/Li and $LiFePO_{4}-TiO_{2}/SPE/Li$ cells were characterized by a cyclic voltammetry and charge/discharge cycling. The electrode with $LiFePO_{4}-carbon-TiO_{2}$ in PVDF-PC-EC-$LiClO_{4}$ electrolyte showed promising capacity of above 100 mAh/g at 1C rate.

Improvement of Electrochemical Properties and Thermal Stability of a Ni-rich Cathode Material by Polypropylene Coating

  • Yoo, Gi-Won;Son, Jong-Tae
    • Journal of Electrochemical Science and Technology
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    • 제7권2호
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    • pp.179-184
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    • 2016
  • The interface between the surface of a cathode material and the electrolyte gives rise to surface reactions such as solid electrolyte interface (SEI) and chemical side reactions. These reactions lead to increased surface resistance and charge transfer resistance. It is consequently necessary to improve the electrochemical characteristics by suppressing these reactions. In order to suppress unnecessary surface reactions, we coated cathode material using polypropylene (PP). The PP coating layer effectively reduced the SEI film that is generated after a 4.3 V initial charging process. By mitigating the formation of the SEI film, the PP-coated Li[(Ni0.6Co0.1Mn0.3)0.36(Ni0.80Co0.15Al0.05)0.64)]O2(NCS) electrode provided enhanced transport of Li+ ions due to reduced SEI resistance (RSEI) and charge transfer resistance (Rct). The initial charge and discharge efficiency of the PP-coated NCS electrode was 96.2 % at a current density of 17 mA/g in a voltage range of 3.0 ~ 4.3 V, whereas the efficiency of the NCS electrode was only 94.7 %. The presence of the protective PP layer on the cathode improved the thermal stability by reducing the generated heat, and this was confirmed via DSC analysis by an increased exothermic peak.

Preparation of rGO-S-CPEs Composite Cathode and Electrochemical Performance of All-Solid-State Lithium-Sulfur Battery

  • Chen, Fei;Zhang, Gang;Zhang, Yiluo;Cao, Shiyu;Li, Jun
    • Journal of Electrochemical Science and Technology
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    • 제13권3호
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    • pp.362-368
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    • 2022
  • The application of polymer composite electrolyte in all-solid-state lithium-sulfur battery (ASSLSBs) can guarantee high energy density and improve the interface contact between electrolyte and electrode, which has a broader application prospect. However, the inherent insulation of the sulfur-cathode leads to a low electron/ion transfer rate. Carbon materials with high electronic conductivity and electrolyte materials with high ionic conductivity are usually selected to improve the electron/ion conduction of the composite cathode. In this work, PEO-LiTFSI-LLZO composite polymer electrolyte (CPE) with high ionic conductivity was prepared. The ionic conductivity was 1.16×10-4 and 7.26×10-4 S cm-1 at 20 and 60℃, respectively. Meanwhile, the composite sulfur cathode was prepared with Sulfur, reduced graphene oxide and composite polymer electrolyte slurry (S-rGO-CPEs). In addition to improving the ion conductivity in the cathode, CPEs also replaces the role of binder. The influence of different contents of CPEs in the cathode material on the performance of the constructed battery was investigated. The results show that the electrochemical performance of the all-solid-state lithium-sulfur battery is the best when the content of the composite electrolyte in the cathode is 40%. Under the condition of 0.2C and 45℃, the charging and discharging capacity of the first cycle is 923 mAh g-1, and the retention capacity is 653 mAh g-1 after 50 cycles.

Electrochemical Performance of High-Voltage LiMn0.8Fe0.2PO4 Cathode with Polyacrylonitrile (PAN)-Based Gel Polymer Electrolyte

  • Kwon, O. Hyeon;Kim, Jae-Kwang
    • Korean Chemical Engineering Research
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    • 제57권4호
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    • pp.547-552
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    • 2019
  • Electrochemical properties of $LiMn_{0.8}Fe_{0.2}PO_4$ cathode were investigated with gel polymer electrolyte (GPE). To access fast and efficient transport of ions and electrons during the charge/discharge process, a pure and well-crystallized $LiMn_{0.8}Fe_{0.2}PO_4$ cathode material was directly synthesized via spray-pyrolysis method. For high operation voltage, polyacrylonitrile (PAN)-based gel polymer electrolyte was then prepared by electrospinning process. The gel polymer electrolyte showed high ionic conductivity of $2.9{\times}10^{-3}S\;cm^{-1}$ at $25^{\circ}C$ and good electrochemical stability. $Li/GEP/LiMn_{0.8}Fe_{0.2}PO_4$ cell delivered a discharge capacity of $159mAh\;g^{-1}$ at 0.1 C rate that was close to the theoretical value ($170mAh\;g^{-1}$). The cell allows stable cycle performance (99.3% capacity retention) with discharge capacity of $133.5mAh\;g^{-1}$ for over 300 cycles at 1 C rate and exhibits high rate-capability. PAN-based gel polymer is a suitable electrolyte for application in $LiMn_{0.8}Fe_{0.2}PO_4/Li$ batteries with perspective in high energy density and safety.