• Journal of the Semiconductor & Display Technology
• /
• v.7 no.4
• /
• pp.45-49
• /
• 2008

For the commercialization of polymer electrolyte membrane fuel cell (PEMFC), some serious problems such as the decrease of platinum use as catalysts and a larger overpotential of oxygen reduction reaction (ORR) at cathode must be solved. In this study, 20%Pt/C and 20%PtCo/C catalysts for the cathode of PEMFC were synthesized from the chemical reduction method and evaluated using an electrochemical measurement. The ORR activity of synthesized 20%Pt/C and 20%PtCo/C had higher than that of the 20%Pt/C on the market. The synthesized 20%PtCo/C with the cobalt concentration (Pt:Co atomic ratio) from 5 to 20% showed the highest ORR activity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.424-425
• /
• 2005

The purpose of this study is to research and develop $LiFe_xMn_{1-x}PO_4$ cathode for lithium polymer batteries. $LiFe_xMn_{1-x}PO_4$ cathode active materials were prepared using a solid-state reaction by adding carbon black to the synthetic precursors. We investigated cyclic voltammetry and charge/discharge cycling of $LiFe_xMn_{1-x}PO_4$/SPE/Li cells. The discharge capacity of $LiFe_{0.5}Mn_{0.5}PO_4$ was l26mAh/g and 110mAh/g at 1st and 10th cycle.

• 한국전기화학회:학술대회논문집
• /
• 1998.10a
• /
• pp.80-80
• /
• 1998

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.359-362
• /
• 2000

The purpose of this study is to research and develop graphene composite for lithium polymer battery. VO(graphene) composite is one of the promising material as a electrode active material for lithium polymer battery(LPB). We investigated AC impedance response and charge/discharge cycling of VO(graphene)/SPE/Li cells. The first discharge capacity of VO(graphene) cathode with 50wt.% V$_2$O$\sub$5/ was 150mAh/g, while that of VO(graphene) cathode with 85wt.% V$_2$O$\sub$5/ was 248mAh/g. The Ah efficiency was above 98% after the 2nd cycle. The discharge capacity of VO(graphene) anode with 3wt.% V$_2$O$\sub$5/ was 718 and 266mAh/g at cycle 1 and 10 at room temperature, respectively. The VO(graphene) anode with 3wt.% V$_2$O$\sub$5/ in PVDF-PAN-PC-EC-LiC1O$_4$ electrolyte showed good capacity with cycling.

• Korean Chemical Engineering Research
• /
• v.59 no.1
• /
• pp.16-20
• /
• 2021

Since the durability evaluation for improving the durability of PEMFC polymer membranes is very important for the development of PEMFC, research and development of the polymer membrane durability evaluation protocol (AST) continues. Recently, DOE's polymer membrane chemical/mechanical durability evaluation AST was developed and applied to Nafion XL for review. In order to shorten the evaluation time, oxygen was used as a cathode gas instead of air, and it was finished in 144 hours. Since DOE AST has a large number of voltage changes with 45 seconds of humidification and 30 seconds of drying, the degradation of the electrode has more influence on the MEA durability. Therefore, one cycle time was lengthened with 60sec of wet/300sec of dry, and the drying time was made longer than the humidification time to further deteriorate the polymer membrane, and it was finished in 240 hours. It was confirmed that the DOE AST for evaluation of the durability of the polymer membrane was accompanied by electrode degradation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05a
• /
• pp.23-26
• /
• 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 $LiOH{\cdot}H_2O$ and $Mn_2O_3$ at various temperature under argon atmosphere. The powders were characterized by the X -ray diffraction. 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 o-$LiMnO_2$ cell was achieved. The capacity of o-$LiMnO_2$ electrode demonstrated better than of the spinel $LiMnO_2$ by solid-state reaction.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.72-72
• /
• 2010

Recent development of organic solar cell approaches the level of 8% power conversion efficiency by the introduction of new materials, improved material engineering, and more sophisticated device structures. As for interface engineering, various interlayer materials such as LiF, CaO, NaF, and KF have been utilized between Al electrode and active layer. Those materials lower the work function of cathode and interface barrier, protect the active layer, enhance charge collection efficiency, and induce active layer doping. However, the addition of another step of thin layer deposition could be a little complicated. Thus, on a typical solar cell structure of Al/P3HT:PCBM/PEDOT:PSS/ITO glass, we used Li:Al alloy electrode instead of Al to render a simple process. J-V measurement under dark and light illumination on the polymer solar cell using Li:Al cathode shows the improvement in electric properties such as decrease in leakage current and series resistance, and increase in circuit current density. This effective charge collection and electron transport correspond to lowered energy barrier for electron transport at the interface, which is measured by ultraviolet photoelectron spectroscopy. Indeed, through the measurement of secondary ion mass spectroscopy, the Li atoms turn out to be located mainly at the interface between polymer and Al metal. In addition, the chemical reaction between polymer and metal electrodes are measured by X-ray photoelectron spectroscopy.

• Journal of the Korean Electrochemical Society
• /
• v.24 no.1
• /
• pp.1-6
• /
• 2021

In this study, new morphology of NCA cathode material for lithium ion batteries was obtained through the electrospinning method. The prepared NCA nanofibers formed a nano-bush structure, and the primary particles were formed on the surface of the nanofibers. The embossing primary particles increased the surface area thus increasing the reactivity of lithium ions. The nano-bush structure could shorten the Li+ diffusion path and improve the Li+ diffusion coefficient. Scanning electron microscopy (SEM) revealed that the synthesized material consisted of nanofibers. The surface area of the nanofibers increased by primary particles was measured using atomic force microscopy (AFM). X-ray diffraction (XRD) analysis was carried out to determine the structure of the NCA nanofibers.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1034-1037
• /
• 2006

We have developed a novel thin film encapsulation method for thin-cathode OLED by introducing organic (not polymer)/inorganic multiple thin films to protect device, which is shown to slow down the permeation rate of moisture and oxygen. From the stability test of devices, the projected lifetime of thin-cathode OLED device with thin film encapsulation was similarly to that with glass lid encapsulation.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.394-394
• /
• 2009

Water solubility of conjugated polymers may offer many applications. Potential applications of water-soluble conjugated polymers include the polymer light-emitting diode and new materials for nano and micro hollow-capsules, and bio- or chemo-sensors. We synthesized neutral polyfluorenes containing bromo-alkyl groups by the palladium catalyzed Suzuki coupling reaction. Bromo-alkyl side groups in neutral polyfluorenes were quaternized by tri-methyl amine solution. The electrochemical and optical properties of water-soluble conjugated polymers are discussed. This novel synthesized water-soluble conjugated polymers were used as a interfacial dipole layer between active layer and metal cathode in polymer solar cell for enhancement of open-circuit voltage (Voc), which is one of the most critical factors in determining device characteristics. We also investigated the device performance of polymer solar cell with different metal cathode such as Al, Ag, Au and Cu. In polymer solar cell, novel cationic water-soluble conjugated polymers were inserted between active layer and high-work function cathode (Al, Ag, Au and Cu).