• Title, Summary, Keyword: Electrolyte Amount

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Analysis of Cell Performance with Varied Electrolyte Species and Amounts in a Molten Carbonate Fuel Cell

  • Lee, Ki-Jeong;Kim, Yu-Jeong;Koomson, Samuel;Lee, Choong-Gon
    • Journal of Electrochemical Science and Technology
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    • v.9 no.2
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    • pp.141-148
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    • 2018
  • This study evaluated the performance characteristics of varied electrolyte species and amounts in a molten carbonate fuel cell (MCFC). Coin-type MCFCs were used at the condition of $650^{\circ}C$ and 1 atm. In order to measure the effects of varied electrolyte species and amounts, electrolytes of $(Li+K)_2CO_3$ and $(Li+Na)_2CO_3$ were selected and the amounts of 1.5 g, 2.0 g, 3.0 g, and 4.0 g were used. Insignificant performance differences were observed in the cell using different electrolytes, but the cell performance was sensitive to the amount of the electrolyte used. The pore-filling ratio (PFR), a ratio of pore filling in the components by the liquid carbonate electrolytes, was used to determine the optimum performance range. Consequently, 77% PFR demonstrated the optimum performance for both electrolytes. Thus, the MCFC had a permissible but narrow optimum performance range. The remaining amounts of electrolyte in the cells were determined using the weight reduction ratio (WRR) method after several hours of cell operation. The WRR used the relationship between the initial loaded amount of electrolyte and weight reduction of components in 10 wt% acetic acid. The relationships were linear and identical between the two electrolyte species.

Performance of molten carbonate fuel cell with Li-Na and Li-K carbonate electrolyte at extremely high-temperature condition

  • Lee, Ki-Jeong;Kim, Tae-Kyun;Koomson, Samuel;Lee, Choong-Gon
    • Korean Journal of Chemical Engineering
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    • v.35 no.10
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    • pp.2010-2014
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    • 2018
  • The cell performance of Li-K and Li-Na carbonate electrolytes was compared using a coin type molten carbonate fuel cell operated at the extremely high temperature of $800^{\circ}C$. It was an acceleration test to compare the performance in a short period. Electrochemical techniques such as steady state polarization (SSP) and impedance from the Nyquist plot were used in the cell performance analysis. The initial performance of both electrolytes was similar, but the performance of the Li-K electrolyte decreased drastically after 180 h. The results from SSP showed that the total overpotential of the Li-K electrolyte increased sharply, whereas that of Li-Na electrolyte had a continuous performance up to 340 h. The impedance analysis showed that the internal resistance of the Li-K electrolyte increased with time, but that of Li-Na electrolyte remained unchanged. The remaining amount of each electrolyte was determined, and it was observed that the electrolyte loss rate of the Li-K electrolyte was 0.0072 g/hr, and that of Li-Na electrolyte was 0.0028 g/hr. This implies that the electrolyte depletion rate of the Li-K electrolyte is about 1.5 times faster than that of the Li-Na electrolyte at the high-temperature condition. Thus, the cell of a Li-Na electrolyte containing MCFC according to the consumption of electrolyte is expected to be longer than one that uses Li-K electrolyte.

Effect of KOH Electrolyte and H2O2 Depolarizer on the Power Characteristics of Al/Air Fuel Cells (Al/Air 연료전지의 출력특성에 미치는 KOH 전해질과 H2O2 감극제의 영향)

  • Kim, Yong-Hyuk
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.64 no.4
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    • pp.303-307
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    • 2015
  • The effects of additive such as $H_2O_2$ in KOH electrolyte solution for the Aluminum/Air fuel cell were investigated with regard to electric power characteristics. The power generated by a Al/Air fuel cell was controlled by the KOH electrolyte solution and $H_2O_2$ depolarizer. Higher cell power was achieved when higher KOH electrolyte concentration and higher $H_2O_2$ depolarizer amount. The maximum power was increased by the increase amount $H_2O_2$ depolarizer, it was found that $H_2O_2$ depolarizer inhibits the generation of hydrogen and the polarization effect was reduced as a result. Internal resistance analysis was employed to elucidate the maximum power variation. Higher internal resistance created internal potential differences that drive current dissipating energy. In order to improve the output characteristics of the Al/Air fuel cell, it is thought to be desirable to increase the KOH electrolyte concentration and increase the $H_2O_2$ addition amounts.

Effect of Electrolyte Concentration on Water Permeation in Protective Coatings (방식도막에 있어서 물의 침투에 대한 전해질 용액의 영향)

  • 박진환
    • Journal of the Korean Society of Safety
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    • v.13 no.4
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    • pp.206-212
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    • 1998
  • The water permeation in protective coatings, which may greatly influence the corrosion protective property of these coatings, was studied using the electrochemical impedance spectroscopy technique. During the absorption of water in protective coatings immersed in electrolyte solution, the change of coating capacitance with concentration of electrolyte was determined from impedance measurements. When water absorption or desorption of coatings occured by exposing the coatings to electrolyte solutions of different concentration, increase in impedance caused by desorption of water was found to be higher in the case of thicker film. The amount of water absorbed in coatings changed with concentration of electrolyte. The water taken up in coatings from the solution of lower electrolyte concentration was deserted by contact with the solution of higher concentration. The uptake of water in protective coatings varied depending on the type of coating ingredient especially binder.

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Effect of Electrolyte Amounts on Electrochemical Properties of Coin-Type Lithium-Ion Cells (액체전해액의 함량에 따른 리튬이온전지 코인셀의 전기화학적 특성 연구)

  • Yoon, Byeolhee;Han, Taeyeong;Kim, Seokwoo;Jin, Dahee;Lee, Yong min;Ryou, Myung-Hyun
    • Journal of the Korean Electrochemical Society
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    • v.21 no.2
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    • pp.39-46
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    • 2018
  • Many studies on the electrochemical performance of Li secondary batteries have been obtained using coin-type cells due to the ease of assembly, low cost and ensuring reproducibility. The coin-type cell consists of a case, a gasket, a spacer disk, and a wave spring. These structural features require a greater amount of liquid electrolyte to assemble than other types of cells such as laminated cells and cylindrical cells. Nevertheless, little research has been conducted on the effect of excess liquid electrolytes on the electrochemical performances of Li secondary batteries. In this study, we investigate the effect of different amounts of electrolyte on the coin-type cells. The amount of electrolytes is adjusted to 30 and $100mg\;mAh^{-1}$. Cycle performances at room temperature ($25^{\circ}C$) and high temperature ($60^{\circ}C$) and high voltage are performed to investigate the electrochemical properties of the different amount of electrolytes. In the case of the unit cell including the electrolyte of $30mg\;mAh^{-1}$, the discharging capacity retention characteristic is excellent in comparison with the case of $100mg\;mAh^{-1}$ under the high temperature and high voltage condition. The former shows a larger increase in internal resistance than the latter, confirming that the amount of electrolyte significantly influences the discharge capacity retention characteristics of the battery.

Preparation and Characteristics of a Matrix Retaining Electrolyte for a Phosphoric Acid Fuel Cell Using Non-volatile Solvent, NMP (비휘발성 용매(NMP)를 사용한 인산형 연료전지(PAFC)용 전해질 매트릭스 제조 및 특성)

  • 윤기현;양병덕
    • Journal of the Korean Ceramic Society
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    • v.37 no.1
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    • pp.26-32
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    • 2000
  • Preparation and characteristics of a matrix retaining electrolyte using SiC whisker, PES binder, and NMP(n-methyl-2-pyrrolidone) as a non-volatile solvent for a phosphoric acid fuel cell were investigated. The conditions of binder and plasticizer, and the effects of substituting a volatile solvent by a non-volatile solvent were also studied. The minimum amount of the binder was about 17 wt% for the proper bubble pressure and surrounding SiC whiskers. And the maximum amount of the plasticizer was about 10wt% to be fitted into the polymer chain of the binder. The matrix prepared by using a non-volatile solvent needed longer time to dry, and its pore size was smaller compared with that of the matrix prepared by using volatile solvent. The small pore size resulted in decrease of the overall pore volume. The ionic conductivity in the condition of the same thickness was decreased due to decrease of phosphoric acid absorbancy. As the internal resistance of the electrolyte increased, the fuel cell performance slightly decreased.

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Recent Research Progress on the Atomic Layer Deposition of Noble Metal Catalysts for Polymer Electrolyte Membrane Fuel Cell (고분자 전해질 연료전지용 촉매 소재 개발을 위한 원자층증착법 연구 동향)

  • Han, Jeong Hwan
    • Journal of Korean Powder Metallurgy Institute
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    • v.27 no.1
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    • pp.63-71
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    • 2020
  • It is necessary to fabricate uniformly dispersed nanoscale catalyst materials with high activity and long-term stability for polymer electrolyte membrane fuel cells with excellent electrochemical characteristics of the oxygen reduction reaction and hydrogen oxidation reaction. Platinum is known as the best noble metal catalyst for polymer electrolyte membrane fuel cells because of its excellent catalytic activity. However, given that Pt is expensive, considerable efforts have been made to reduce the amount of Pt loading for both anode and cathode catalysts. Meanwhile, the atomic layer deposition (ALD) method shows excellent uniformity and precise particle size controllability over the three-dimensional structure. The research progress on noble metal ALD, such as Pt, Ru, Pd, and various metal alloys, is presented in this review. ALD technology enables the development of polymer electrolyte membrane fuel cells with excellent reactivity and durability.

Effects of Electrolyte Concentration on Electrochemical Properties of Zinc-Air Batteries (전해질 농도에 따른 아연-공기 전지의 전기화학적 특성)

  • Han, Ji Woo;Jo, Yong Nam
    • Korean Journal of Materials Research
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    • v.29 no.12
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    • pp.798-803
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    • 2019
  • The self-discharge behavior of zinc-air batteries is a critical issue induced by corrosion and hydrogen evolution reaction (HER) of zinc anode. The corrosion reaction and HER can be controlled by a gelling agent and concentration of potassium hydroxide (KOH) solution. Various concentrations of KOH solution and polyacrylic acid have been used for gel electrolyte. The electrolyte solution is prepared with different concentrations of KOH (6 M, 7 M, 8 M, 9 M). Among studied materials, the cell assembled with 6 M KOH gel electrolyte exhibits the highest specific discharge capacity and poor capacity retention. Whereas, 9 M KOH gel electrolyte shows high capacity retention. However, a large amount of hydrogen gas is evolved with 9 M KOH solution. In general, the increase in concentration is related to ionic conductivity. At concentrations above 7 M, the viscosity increases and the conductivity decreases. As a result, compared to other studied materials, 7 M KOH gel electrolyte is suitable for Zn-air batteries because of its higher capacity retention (92.00 %) and specific discharge capacity (351.80 mAh/g) after 6 hr storage.

Effect of Pt amount in the Pt/C for cathode catalyst on the performance of PEMFC (고분자전해질 연료전지의 환원전극 백금 담지촉매의 백금 담지비에 따른 성능변화)

  • Cho, Yong-Hun;Cho, Yoon-Hwan;Park, Hyun-Seo;Sung, Yung-Eun
    • 한국신재생에너지학회:학술대회논문집
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    • pp.107-109
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    • 2006
  • This study focuses on a determination of amount of Pt in the Pt/C for catalysts of polymer electrolyte membrane fuel cells (PEMFC). PEMFC offer low weight and high power density and being considered for automotive and stationary power applications. The PEMFC performance is influenced by several factors, including catalysts and structure of electrode and membrane type. Catalyst of electrode is important factor for PEMFC. One of the obstacles prevent ing polymer electrolyte membrane fuel cells from commercialization is the high cost of noble metals to be used as catalyst, such as platinum To effectively use these metals, they have to be will dispersed to small particles on conductive carbon supports. The optimal amount of Pt in Pt/C for cathode catalyst was investigated by using polarization curves in single cell with $H_2/O_2$ operation.

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Effect of Fluoroethylene Carbonate in the Electrolyte for LiNi0.5Mn1.5O4 Cathode in Lithium-ion Batteries

  • Kim, Jaemin;Go, Nakgyu;Kang, Hyunchul;Tron, Artur;Mun, Junyoung
    • Journal of Electrochemical Science and Technology
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    • v.8 no.1
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    • pp.53-60
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    • 2017
  • Fluoroethylene carbonate (FEC) was studied as an additive for the electrolyte in lithium ion batteries with the $LiNi_{0.5}Mn_{1.5}O_4$ (LNMO) spinel cathode operating at a high potential beyond 4.7 V (vs. $Li/Li^+$). It was found that the FEC additive was electrochemically active for the $1^{st}$ charge cycle on the LNMO cathode. The presence of a large amount of FEC (more than 40 vol%) in the electrolyte caused severe side reactions with abnormally long voltage plateaus. In contrast, when the electrolyte contained less than 30 vol% FEC, the surface of the LNMO cathode was stabilized by the formation of the solid-electrolyte interphase (SEI), leading to improved cyclability. However, the resistance from the SEI limited the rate capability because of sluggish lithium transportation through the SEI and electronic insulation between the particles in the electrode.