• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.416-422
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• 2015

Lithium Ion capacitor (LIC) is a new storage device which combines high power density and high energy density compared to conventional supercapacitors. LIC is capable of storing approximately 5.10 times more energy than conventional EDLCs and also have the benefits of high power and long cycle-life. In this study, LICs are assembled with activated carbon (AC) cathode and pre-doped graphite anode. Cathode material of natural graphite and artificial graphite kinds of MAGE-E3 was selected as the experiment proceeds. Super-P as a conductive agent and PTFE was used as binder, with the graphite: conductive agent: binder of 85: 10: 5 ratio of the negative electrode was prepared. Lithium doping condition of current density of $2mA/cm^2$ to $1mA/cm^2$, and was conducted by varying the doping. Results Analysis of Inductively Coupled Plasma Spectrometer (ICP) was used and a $1mA/cm^2$ current density, $2mA/cm^2$, when more than 1.5% of lithium ions was confirmed that contained. In addition, lithium ion doping to 0.005 V at 10, 20 and $30^{\circ}C$ temperature varying the voltage variation was confirmed, $20^{\circ}C$ cell from the low internal resistance of $4.9{\Omega}$ was confirmed.

• Journal of the Society of Disaster Information
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• v.16 no.2
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• pp.392-401
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• 2020

Purpose: This study analyzes the operating characteristics of a lithium ion capacitor that can be used as a standby power supply in an emergency, and determines whether the standby power supply is abnormal even by measuring the voltage using a linear proportionality characteristic during charging and discharging. The aim is to provide an experimental basis that can be done. Method: As a method for this study, first, analyze the operation principle and characteristics of the existing backup power supply and lithium ion capacitor, and then measure the voltage of the lithium ion capacitor according to the configuration and system block diagram of the induction lamp used in the experiment. We proceed with the test of the measured value of discharge power for each voltage band to check the amount of power held by the battery and the operation test experiment using induction lamps. Results: Just by checking the charging voltage using the linear proportional characteristics of lithium ion capacitors, it provides a basis for accurately inferring the effective operating time of induction lamp lamps. Conclusion: In the event of a disaster, the lithium ion capacitor is used as a spare power supply for emergency induction lamps to prevent complete discharge of emergency induction lamps, to prevent the problem of performing normal operation of the standby power supply, and to use only a simple voltage measurement to reserve power. It was intended to suggest many uses for evacuation equipment application in the future by making it possible to check whether the device is abnormal.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.167-167
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• 2014

Graphite is used as a negative electrode active material of Lithium ion capacitor (LIC). At the cathod, electrostatic reaction of EDLC is a very high reaction rate compared to a oxidaion reduction reaction. When the graphite was expanded that the length between the sheet, the intercalation of lithium ions is smoothed. And thus, the power density increases. By measuring the XRD, it was confirmed that the increase in interlayer spacing of graphite. And by measuring an electrochemical reactionin Lithium Ion Battery (LIB), it was confirmed the tendency of power density is improved.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.388-389
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• 2017

본 논문에서는 효율적인 에너지 관리를 위해 리튬이온 배터리를 적용 능동 셀 밸런싱 시스템 BMS에 대해 제안하였다. 제안된 방법은 다수의 셀과 하나의 커패시터로 구성된 SSC(Single Switched Capacitor) 방식에서 사용되는 커패시터를 리튬이온 배터리로 변경하여 적용한 것이다. SSC 방식은 커패시터의 방향성으로 인하여 홀수 번째와 짝수 번째의 배터리에 대해 별도의 스위치를 설치하여야 하며 조작이 복잡하다는 단점을 가지고 있었다. 이러한 단점을 보완하여 커패시터를 리튬이온 배터리로 대체하여 셀의 순서에 상관없이 적용이 가능한 셀 밸런싱 방법을 제안하였다. 제안된 방법의 효율성은 BMS를 구현하여 실험 하였다. 실험 결과 셀 밸런싱이 기존의 SSC 방식보다 개선되어 효율성이 입증되었다.

• Journal of Power Electronics
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• v.14 no.5
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• pp.1038-1046
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• 2014

Lithium-ion batteries are widely used in hybrid and pure electric vehicles. State-of-charge (SOC) estimation is a fundamental issue in vehicle power train control and battery management systems. This study proposes a novel model-based SOC estimation method that applies closed-loop state observer theory and a comprehensive battery model. The state-space model of lithium-ion battery is developed based on a three-order resistor-capacitor equivalent circuit model. The least square algorithm is used to identify model parameters. A multi-state closed-loop state observer is designed to predict the open-circuit voltage (OCV) of a battery based on the battery state-space model. Battery SOC can then be estimated based on the corresponding relationship between battery OCV and SOC. Finally, practical driving tests that use two types of typical driving cycle are performed to verify the proposed SOC estimation method. Test results prove that the proposed estimation method is reasonably accurate and exhibits accuracy in estimating SOC within 2% under different driving cycles.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.501-505
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• 2004

The study on the hybrid power source for the IMT2000 application has been presented. The hybrid power source is composed of solar cell, super-capacitor and battery. To compensate for the pulse loader of the IMT2000 application, the super-capacitor is connected through the Lithium-ion battery to absorb the pulse current. The solar cell provides the additional current to compensate for the depleted current. The controller design for the hybrid source has been presented and verified through experiment.

• Journal of the Korean Electrochemical Society
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• v.6 no.3
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• pp.174-177
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• 2003

Electric double-layer capacitors based on charge storage at the interface between a high surface area activated carbon electrode and an electrolyte solution are characterized by their long cycle-life and high power density in comparison with batteries. However, energy density of electric double-layer capacitors obtained at present is about 6 Wh/kg at a power density of 500W/kg which is smaller as compared with that of batteries and limits the wide spread use of the capacitors. Therefore, a new capacitor that shows larger energy density than that of electric double-layer capacitors is proposed. The new capacitor is the hybrid capacitor consisting of activated carbon cathode, carbonaceous anode and an organic electrolyte. Maximum voltage applicable to the cell is over 4.2V that is larger than that of the electric double-layer capacitor. As a result, discharged energy density on the basis of stacked volume of electrode, current collector and separator is more than 18Wh/l at a power density of 500W/l.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.241-243
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• 2007

Two-stage charge equalization scheme for HEV lithium-ion battery string is proposed with the optimal power rating design rule in this paper, where in the first stage the over charged energy of higher voltage cells is drawn out to the single common output capacitor and then, that discharged energy is recovered into the overall battery stack in the second stage. To achieve charge equalization of sort, the conventional flyback DC/DC converters of low power and minimized size are employed. The industrial sample employing both the proposed two-stage cell balancing scheme and the optimal power rating design rule shows good cell balancing performance with reduced size as well as low voltage stresses of the electronic devices.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.283-291
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• 2010

In this review, the studies on the electrochemical properties of $TiO_2$ nanotube as an anode material of lithium-ion battery, which was prepared by an alkaline hydrothermal reaction and anneling process, were investigated andanalyzed in terms of charge-dischage characteristics. Up to date, a maximum discharge capacity of $338mAh\;g^{-1}$(x=1.01) was achieved by the nanotube with $TiO_2(B)$ phase, whereas the theoretical capacity of $TiO_2$ anode was $335mAh\;g^{-1}$(x=1) in the basis of $Li_xTiO_2$ as a product of electrochemical reaction between $TiO_2$ and lithium. This was due to fast lithium transport by a shortened diffusion path provided by controlling the nanostructure of $TiO_2$, because the self-diffusion of lithium was slow in a basis of its activation energy as 0.48 eV. Due to an excellent ion storage capabilities in both the surface and the bulk phase, the $TiO_2$ nanotube could be a promising active material as both an anode of lithium-ion battery and an electrode of capacitor with high-rate performances.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.884-889
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• 2018

In this study, polyaniline $(PANI)/WO_3$ electrode was prepared as an anode of a lithium ion capacitor, and its electrochemical characteristics were measured and analyzed. When PANI was electrochemically deposited on the surface of $WO_3$ electrode, the capacity of $PANI/WO_3$ was improved with increase of the deposited amounts of PANI. Furthermore, the effect of light irradiation on capacity and coulombic efficiency was examined by irradiating sunlight during charging and discharging. When the light was irradiated to the $WO_3$ electrode and the $PANI/WO_3$ electrode, those capacities and coulombic efficiencies were increased compared to that measured under the dark condition. It is attributed to the photocatalytic property of $WO_3$ that can generate photoelectrons by light irradiation. In $PANI/WO_3$ electrode, PANI also can be excited under the light irradiation with affecting the electrochemical property of electrode. The photoelectrons improve the capacity by participating in the intercalation of $Li^+$ ions, and also improve the coulombic efficiency by facilitating electrons' transport. Under the dark condition, the capacity of $PANI/WO_3$ was gradually reduced with increase of cycles due to a poor stability of PANI. However, the stability of PANI was significantly improved by the light irradiation, which is attributed to the oxidation-reduction reaction originated from the photogenerated electrons and holes in $PANI/WO_3$.