• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.22-23
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• 2011

본 논문은 Battery의 열화 특성을 반영한 순차적 Step Charge를 통한, Mobile 기기용 Li-Ion Smart Battery의 Life Cycle 개선기술을 제안 하고자 한다. 현재 기술수준의 Li-Ion 2차전지 수명은 표준충방전 300~500cycle 내외이나. 초기용량을 희생하지 않고도 Smart Battery 내부의 ASOC(Absolute State of Charge)와 연동하여 Battery 수명열화 곡선을 추종하는 최적화된 가변 충전전압을 순차적 Step Charge로 제공하여 Li-Ion 2차 전지의 수명열화를 개선하고, 열화 특성의 검토 및 개선효과 확인을 논문의 목적으로 한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.576-579
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• 2009

This paper suggests a autonomous linear Li-ion battery charger which can safely distribute power between an external power source(AC adapter, auto adapter, or USB source), battery, and the system load. Depending on an external power source's capability, the charger selects proper charging-mode automatically. The charger IC designed and fabricated on Dongbu HITEC's $0.35{\mu}m$ BCD process with layers of one poly and three metals.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.27-28
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• 2009

This paper suggests a autonomous linear Li-ion battery charger which can safely distribute power between an external power source(AC adapter, auto adapter, or USB source), battery, and the system load. Depending on an external power source's capability, the charger selects proper charging-mode automatically. The charger IC designed and fabricated on Dongbu HITEC's $0.35{\mu}m$ BCD process with layers of one poly and three metals.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.49-57
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• 2013

In this study, we fabricated a parallelly connected Li-ion battery/supercapacitor hybrid cell to combine the advantageous characteristics of Li-ion battery and supercapacitor, high energy density and high power density, respectively, and investigated its discharging characteristics over a wide temperature range from -40 to $25^{\circ}C$. At the initial state of discharging of the hybrid cell, the power was mostly provided by the supercapacitor and then the portion of the Li-ion battery was gradually increased. By installing a switching system into the hybrid cell, which controls the discharging sequence of Li-ion battery and supercapacitor, the maximum power was improved by 40% compared with non switching system. In addition at low temperatures, the power and discharging time of the hybrid cell were significantly enhanced compared to a battery-alone system. The hybrid cell is expected to be applied in electric vehicles and small domestic appliances that require high power at initial discharging state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.597-598
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• 2005

Recently, the performance of portable electric equipment can often improved by a Li-ion battery assisted by a supercapacitor. A supercapacitor can provide high power density as well as a low resistance in the hybrid system. In this study, we have prepared, as the pluse power souce, a commercially supplied Li-ion battery with a capacity of 700mAh and AC resistivity of $60m\Omega$ at 1kHz and nonaqeous asymmetric hybrid capacitor composed of an activated carbon cathode and MCMB anode, and have examined the electrochemical characteristics of hybrid capacitor and the pulse performances of parallel connected battery/hybrid capacitor source. The nonaqueous asymmetric hybrid capacitor, the stacks of 10 pairs of the cathode, the porous separator and the anode electrode were housed in Al-laminated film cell. The hybrid capacitor, which was charged and discharged at a constant current at $0.25mA/cm^2$ between 3 and 4.3V, has exhibited the capacitance of 100F. And the equivalent series resistance was $32m\Omega$ at 1kHz. By combining a Li-ion battery and a hybrid capacitor, the pulse performance of battery can be improved 23% in run time under a pulse discharge of 7C-rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.855-863
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• 2017

Because Li-ion battery and Li-Polymer battery have high-energy storage density, they are used for various electronic devices such as electronic cigarette, electronic bicycle, drone, second battery, even golf cart and electronic car. Recently, however, battery explosion is sometimes occurring on electronic devices using Li-ion battery and is becoming serious as bodily harm is breaking out due to explosion. For this, this paper described the Li-ion Battery's operating principles and verified the cause of explosion by overload tests caused by the high-energy storage density. According to the these experiments, we conducted a study to develope scanning techniques of fire and safety measures.

• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.290-294
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• 2010

We performed a density functional theory study to investigate the intercalation voltage and lithium ion conduction in lithium cobalt oxide for lithium ion battery as a function of the lithium concentration. There were two methods for the intercalation of lithium ions; the intercalation of a lithium ion at a time in the individual layer and the intercalation of lithium ions in all the sites of one layer after all the sites of another layer. The average intercalation voltage was the same value, 3.48 V. However, we found the former method was more favorable than the latter method. The lattice parameter c was increased as the increase of the lithium concentration in the range of x < 0.25 while it was decreased as increase of the lithium concentration in the range of x > 0.25. The energy barrier for the conduction of lithium ion in lithium cobalt oxide was increased as the lithium concentration was increased. We demonstrated that the decrease of the intercalation voltage and increase of the energy barrier as the increase of the lithium concentration caused lower output voltage during the discharge of the lithium ion battery.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.11
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• pp.77-83
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• 2014

The Estimation of State of Charge(SOC) for batteries is an important aspect of a Battery Management System(BMS). A method for estimating the SOC is proposed in order to overcome the individual disadvantages of the current integral and Open Circuit Voltage(OCV) estimation methods by combining them using Extended Kalman filter(EKF). The non-linear characteristics of the Li-Ion RC battery model used in this study is also solved through EKF. The proposed method is simulated in a Matlab environment with a Li-Ion Kokam battery (3.7V, 1,500mAh). Results showed that there is an improvement in the estimation error when using the proposed model compared to the conventional current integral method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.90-95
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• 2009

This paper presents a new lithium ion unit-cell and pack battery by using a new formulation ratio of material. The three types of formulation ratio for the unit-cell were used. The life cycle and basic properties of the lithium ion unit-cell$({\Psi}18{\times}65(mm))$ about one of them were acquired by the charge-discharge experiment. The nominal voltage, nominal capacity and cycle life output of the lithium ion unit-cell is respectively 3.7V, 2.4Ah, and above 500cycle. Pack type lithium ion battery has the size of $29.5{\times}73.5{\times}115(mm)$ and the weight of 300g. As the results, the weight and bulk of lithium ion battery used to a safety lamp were decreased to 1/4 and 1/7. In addition, the comparison of the new lithium ion battery and lead storge battery for confirming the effectiveness of the new lithium ion battery have been performed.

• Membrane Journal
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• v.14 no.4
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• pp.263-274
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• 2004

The polymeric membrane, a component of battery devices such as Li-ion battery (LIB) and Li-polymer battery (LPB), is a typical material in which the carrier mobility dominates the battery performance. In this paper, the state-of-the-art of membranes for secondary battery is described in terms of membrane properties. Several prerequisites, which are related to stability of battery devices, are discussed to design and prepare suitable polymeric membranes. In addition, physical requirements of membranes and their measurement methods are described to develop applicable polymeric membranes in membrane preparation processes.