• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.2
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• pp.142-147
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• 2005

In this work, a gel polymer electrolyte (GPE) was prepared using polyoxyalkylene glycol acrylate (POAGA) as a macromonomer LiCoO$_2$/GPE/graphite cells were prepared and their electrochemical properties were evaluated at various current densities and temperatures. The ionic conductivity of the GPE was more than 6.2${\times}$10$^{-3}$ S$.$$cm^{-1}$ / at room temperature. The GPE had good electrochemical stability up to 4.5 V vs. Li/Li$^{+}$. POAGA-based cells were showed good electrochemical performances such as rate capability, low-temperature performance, and cycleability. The cells, also, passed a safety test such as the overcharge and nail-penetration test.t.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.463-464
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• 2017

다른 리튬계열 전지와 달리, 인산철($LiFePO_4$) 배터리는 중간 동작 영역에서 개방전압(OCV; open-circuit voltage)의 히스테리시스(hysteresis) 영역이 존재한다. 그러므로, 인산철 배터리 관리시스템, 특히 충전상태(SOC; state-of-charge)와 수명상태(SOH; state-of-health)의 정확한 모니터링을 위해서는 OCV의 정밀성이 요구된다. 본 논문에서는, 충전 및 방전 OCV-SOC의 SOC 간격에 따른 인산철 배터리의 SOH를 비교하기 위해 전기적 등가회로 모델(ECM; electrical-circuit modeling)적응제어 알고리즘 기반 실시간 내부저항(DCIR; direct current internal resistance)을 모니터링 하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.79-84
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• 1993

This paper describes the development of lithium rechargeable cell. $LiCoO_2$ is recently recognized as a suitable cathode active material of a high voltage, high energy lithium rechargeable batteries because $Li^+$ ion can be electrochemically deintercalated/intercalated from/to $Li_xCoO_2$. The transition metal oxide of $LiCoO_2$ was investigated for using as a cathode active material of 4V class Li rechargeable cell. $LiCoO_2$ cathode was prepared by using a active material of 85 wt%, graphite powder of 12 wt% as a conductor and poly-vinylidene fluoride of 3 wt% as a binder. The electrochemical and charge/discharge properties of $LiCoO_2$ were investigated by cyclic voltammetry and galvanostatic charge/discharge. The open circuit voltage of prepared $LiCoO_2$ electrode exhibited approximately. potential range between 3.32V and 3.42V. During the galvanostatic charge/discharge, $LiCoO_2/Li$ cell showed stable cycling behavior at scan rate of 1mV/sec and potential range between 3.6V and 4.2V. Also its coulombic efficiency as function of cycling was 81%~102%. In this study the $LiCoO_2/Li$ cell showed the available discharge capacity of 90.1 mAh/g at current density of $1mA/cm^2$ and cell discharge voltage range between 3.6V~4.2V.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.83-91
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• 2011

We investigated the effect of composition of a sulfur electrode with MWNT on the discharge behavior and cycling property of a Li/S cell. The MWNT content of a 60wt.% sulfur electrode varied from 10 wt.% to 30 wt.%. The optimum content of MWNT is 20wt.%, which shows the best cycling property. The first discharge capacity is 1166 mAh/g and decrease to the 542 mAh/g after 30th cycle. The homogeneous distribution of MWNT is an important factor for cycling properties.

• Journal of the Korean Electrochemical Society
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• v.22 no.1
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• pp.22-35
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• 2019

Development of low cost rechargeable batteries has been considered as a significant task for future large-scale energy storage units (i.e. electric vehicles, smart grids). Sodium-ion batteries (SIBs) have been recognized as a promising alternative to replace conventional lithium-ion batteries (LIBs) because of their abundancy and economic benign. Nevertheless, Na ions have larger ionic radius than that of Li ions, resulting in sluggish transport of Na ions in electrodes for cell operation. There have been efforts to seek suitable anode materials for the past years operated based on three different kinds of reaction mechanism (intercalation, alloy reaction, and conversion reaction). In this review, we introduce a class of conversion reaction anode materials for Na-ion batteries, which have been reported.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.69.2-69.2
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• 2010

Recently, bulk hetero-junction cells have been extensively studied by many researchers. Most of these cells were fabricated by spin coater. However, the spin coating process is not favorable to the large-scaled industry because it is not compatible with roll-to-roll process. One of the alternative methods is Doctor blading. In this study, we fabricated large OPV cells having total area of $100cm^2$. The buffer layer was Poly-(3,4-ethylenedioxythiophene) : poly-(styrenesulfonate) aqueous dispersion (PEDOT:PSS) and the active material is poly (3-hexythiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blend in the solvent of Chlorobenzene. All of the organic layers were coated by dragging the blade with a speed of 5~20 mm/s on the stage with a temperature of $50^{\circ}C$. As-bladed PEDOT:PSS layer was baked at $120^{\circ}C$ for 10 minutes to eliminate the water. The cell structure is patterned ITO substrate/PEDOT:PSS/P3HT:PCBM/LiF/Al. The topmost electrode, LiF/Al, was deposited by thermal evaporation. After depositing electrode, and the cell was annealed at $150^{\circ}C$ for 30 minutes. The measured ISC, VOC, fill factor, and PCE were 2.95 A, 5.86 V, 0.32, and 0.78%, respectively. PCE was quite low but the large active area could be obtained successfully.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.339-342
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• 2000

Polypyrrole(PPy) nanotubules were formed within template pores by chemical synthesis using $FeCl_3$ as an oxidant. The oxidation peak of PPy nanotubules in the cyclic voltammogram was observed at about 2.8V and 3.3V vs. $Li/Li^+$, while in the case of PPy film, that was observed at about 3.0V. It suggests that the electron hopping on the main chain of PPy nanotubules was improved. When the PPy nanotubules was used to a cathode of lithium secondary battery, we obtained discharge capacity as much as 27 mAh/g, and initial coulomb efficiency by 90%. We expect that the capacity can be improved by further study.

• Analytical Science and Technology
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• v.10 no.3
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• pp.209-215
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• 1997

Li-AGICs as a anode of secondary battery were synthesized by high-pressure method as a function of the Li-contents. The characteristics of these prepared compounds were determined from the studies with X-ray diffraction method, UV/VIS spectrophotometric and differential scanning calorimeter(DSC) analysis. From the results of X-ray diffraction, it was found that the lower stage intercalation compounds were formed with increase of Li-contents. The mixed stages in these compounds were also observed. In the case of the $Li_{30wt%}$-AGIC, the compounds in the stage 1 structure were formed predominantly, but the structure of only pure stage 1 for structural defect of artificial graphite is not observed. According to UV/VIS spectrophotometric analysis, $Li_{30wt%}$-AGIC shows distinguishable energy state spectrum with the position of $R(%)_{min}$ values, but the characteristic spectra of almost all Li-AGICs are not observed. The enthalpy and entropy changes of the compounds can be obtained from the differential scanning calorimetric analysis results. From the results, it was found that exothermic and endothermic reactions of Li-AGICs are related to thermal stability of lithium between artificial graphite layers.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.165-170
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• 2005

Al-Zn alloy/$MnO_2$, seawater cell was considered as a primary aqueous cell with an average voltage range from 1.0 to 1.1V, and the electrolyte of seawater was uptaken into the cell. Eventually, the capacity of its usage will be used for long-term. However, the more use of this cell, the higher corrosion phenomenon of the electrode occurred. Due to its corrosion phenomenon, one main default has been observed with gradual decrease during a discharge process. In this research, a common-used active material for anode was $LiNiO_2$. An active material for cathode, $Zn_{X}FeS_2$ was synthesized in high temperature by uptaken a small amount of 1.3 wt% of ZnS into $FeS_2$, one of the transition-metal dichalcogenides in high temperature. Consequently, based on their usages shown above, this secondary aqueous lithium cell could be more developed. This cell was shown as remarkable charge/discharge performance during the charge/discharge processes. This cathode with active material was given a considerable efficiency of inserting $Li^+$ ions. Moreever, in accordance with the characteristic of the crystal structure for $Zn_{x}FeS_2$, a small amount of ZnS was added which made it possible to reduce prominently velocity of corrosion during the charge/discharge cycle. By applying those merits, Al-Zn alloy/$MnO_2$ seawater cell will be used as a fundamental data in order to transform into a secondary aqueous cell.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.78-85
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• 2019

The effect of various lithium sources such as LiCl, LiOH, and Li-metal on the microstructure and electrochemical properties of granulated $SiO_x$ powders were investigated. Various lithium sources were metallurgically added for a passive pre-lithiation of $SiO_x$ to improve its low initial coulombic efficiency. In spite of using the same amount of Li in various sources, as well as the same process conditions, different lithium silicates were obtained. Moreover, irreversible phases were formed without reduction of $SiO_x$, which might be from additional oxygen incorporation during the process. Accordingly, there were no noticeable electrochemical enhancements. Nevertheless, the $Li_4SiO_4$ phase changes the initial electrochemical reaction, and consequently the relationship between the microstructure and electrochemical properties of metallurgically pre-lithiated $SiO_x$ could provide a guideline for the optimization of the performance of lithium ion batteries.