• 한국전기전자재료학회논문지
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• 제18권2호
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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.

• 한국전기전자재료학회논문지
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• 제16권11호
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• pp.994-1000
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• 2003

In this study, gel polymer electrolytes (GPE) with semi-interpenerating network of poly (methyl methacrylate) and hexanediol dimethacrylate were synthesized and their electrochemical performances were evaluated. LiCoO$_2$/GPE/graphite cells were prepared and their performances depending on discharge currents and temperatures were evaluated. The precursor containing 5 vol% curable mixture had a low viscosity relatively. GPE showed good electrochemical stability up to potential of 4.8 V vs. Li/Li$\^$+/. Ionic conductivity of the gel polymer electrolyte at room temperature and -20$^{\circ}C$ was ca. 5.9 and 1.4${\times}$10$\^$-3/ Scm$\^$-1/, respectively. LiCoO$_2$/GPE/graphite cells showed good rate capability, low-temperature performance and cycleability.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.249-251
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• 2009

In this paper, we present a study on the 50kW class power station development using lithium-polymer battery. The 50kW class power station purposes to compensate for peak load using 326[V] lithium-polymer battery bank. The output voltage is 380[V] in three-phase, peak load compensation is controlled based on load power. Finally, a 50kW power station system is built to verify the experiment.

• 전력전자학회논문지
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• 제18권1호
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• pp.26-36
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• 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.

• 한국고분자학회지:고분자과학과기술
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• 제9권2호
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• pp.131-136
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• 1998

• 한국고분자학회지:고분자과학과기술
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• 제9권2호
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• pp.104-110
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• 1998

• Bulletin of the Korean Chemical Society
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• 제22권10호
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• pp.1136-1140
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• 2001

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.269-272
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• 1997

The Lithium ion secondary battery has been developed for high energy density of portable electrical device and electronics. Among the many conductive polymer materials, the positive active film for Li polymer battery system was synthesized successfully from polyphenylene diamine(PPD) by chemical polymerization in our lab. And PPD-DMcT(2, 5-dimercapto-1, 3, 4-thi-adiazole) composite flim conductive material, at high temperature was also prerared with the addition of dimethylsulfoxide(DMSO). The surface morphology and thermal stability of prepared composite flim was carried out by using SEM and TGA, respectively. Electrochemical and electrical conductivity of composite flim were also discussed by cyclic voltammetry and four-probe method in dry box(<27pm). And the electrode reaction mechanism was detected and analyzed from the half cell unit battery system.

• Journal of Power Electronics
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• 제11권2호
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• pp.237-243
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• 2011

Lithium batteries are widely used in mobile electronic devices due to their higher voltage and energy density, lighter weight and longer life cycle when compared to other secondary batteries. In particular, a high demand for lithium batteries is expected for electric cars. In the case of the lithium batteries used in electric cars, driving distance must be calculated accurately and discharging should not be done below a level that makes it impossible to crank. Therefore, accurate information on the state-of-charge (SOC) becomes an essential element for reliable driving. In this paper, a novel method for estimating the SOC of lithium polymer batteries using AC impedance is proposed. In the proposed method, the parameters are extracted by fitting the measured impedance spectrum on an equivalent impedance model and the variation in the parameter values at each SOC is used to estimate the SOC. Also to shorten the long length of time required for the measurement of the impedance spectrum, a novel method is proposed that can extract the equivalent impedance model parameters of lithium polymer batteries with the impedance measured at only two specific frequencies. Experiments are conducted on lithium polymer batteries, with similar capacities, made by different manufacturers to prove the validity of the proposed method.