• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 심포지엄 논문집 정보 및 제어부문
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• pp.150-152
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• 2004

The battery charge/discharge process, the final step of the secondary battery production process, requires real-time precision controls for improving both lifetime and performance of the battery cell. In this paper, we present embedded system design for precision control of the secondary battery charge/discharge production process using low power embedded processor based on embedded linux. This system receive charge/discharge command from the main server through ethernet. Compared to existing charge/discharge control system, our design makes low cost and precision control system possible.

• 전력전자학회논문지
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• 제14권5호
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• pp.387-396
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• 2009

리튬전지는 생산과정에서의 핵심인 화성공정에 의해 수명 및 성능이 크게 좌우되며, 화성공정을 처리하기 위해서 충방전 시스템이 필수적으로 요구되고 있다. 리튬전지 충방전 시스템의 특성을 해석하기 위해 일반적인 방법으로 시뮬레이션하면 충전동작과 방전동작에 엄청난 시간이 소요되고 메모리 용량의 한계로 인해 범용 PC로는 시뮬레이션이 어렵다. 본 논문에서는 리튬전지를 저항-커패시터 직렬회로로 모델링하였으며 상태공간평균의 개념을 적용하여 리튬전지 충방전 시스템을 해석하고 시뮬레이션하였다. Simplorer를 사용하여 시뮬레이션을 수행한 결과 시뮬레이션 시간이 단축되어 범용 PC로도 3시간 내에 시뮬레이션이 가능해졌으며, 리튬전지 충방전 시스템의 정전류/정전압 충전 특성 및 정전류 방전 특성과 충방전 소요시간을 예측할 수 있었다. 또한 충방전 시스템을 구성하고 실험하여 리튬전지를 저항-커패시터 직렬회로로 등가화한 모델링의 타당성과 상태공간평균의 개념을 사용하여 해석하고 시뮬레이션한 방법의 유용성을 입증하였다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1102-1106
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• 2015

A hybrid supercapacitor (HS) is an energy storage device used to enhance the low weight energy density (Wh/kg) of a supercapacitor. On the other hand, a sudden decrease in capacity has been pointed out as a reliability problem after many charge/discharge cycles. The reliability problem of a HS affects the early aging process. In this study, the capacity performance of a HS was observed after charge/discharge. For detailed analysis of the initial charge/discharge cycles, the charge and discharge curve was measured at a low current density. In addition, a solid electrolyte interphase (SEI) layer was confirmed after the charge/discharge. A HC composed of a lithium titanate (LTO) anode and active carbon cathode was used. The charge/discharge efficiency of the first cycle was lower than the late cycles and the charge/discharge rate was also lower. This behavior was induced by SEI layer formation, which consumed Li ions in the LTO lattice. The formation of a SEI layer after the charge/discharge cycles was confirmed using a range of analysis techniques.

• 한국재료학회지
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• 제26권12호
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• pp.696-703
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• 2016

In this study, we intensively investigated the effect of conductive additive amount on electrochemical performance of organic supercapacitors. For this purpose, we assembled coin-type organic supercapacitor cells with a variation of conductive additive(carbon black) amount; carbon aerogel and polyvinylidene fluoride were employed as active material and binder, respectively. Carbon aerogel, which is a highly mesoporous and ultralight material, was prepared via pyrolysis of resorcinol-formaldehyde gels synthesized from polycondensation of two starting materials using sodium carbonate as the base catalyst. Successful formation of carbon aerogel was well confirmed by Fourier-transform infrared spectroscopy and $N_2$ adsorption-desorption analysis. Electrochemical performances of the assembled organic supercapacitor cells were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements. Amount of conductive additive was found to strongly affect the charge transfer resistance of the supercapacitor electrodes, leading to a different optimal amount of conductive additive in organic supercapacitor electrodes depending on the applied charge-discharge rate. A high-rate charge-discharge process required a relatively high amount of conductive additive. Through this work, we came to conclude that determining the optimal amount of conductive additive in developing an efficient organic supercapacitor should include a significant consideration of supercapacitor end use, especially the rate employed for the charge-discharge process.

• 전력전자학회논문지
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• 제15권6호
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• pp.441-450
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• 2010

리튬전지는 다양한 전자기기의 구동전원으로 널리 사용되고 있으며, 충전과 방전 동작을 수차례 반복하는 화성공정은 이러한 리튬전지의 생산에 필수적이다. 본 논문에서는 충전동작과 방전동작을 하나의 장치로 수행할 수 있는 리튬전지 충방전용 직류-직류 변환기를 제안하고 설계한다. 제안한 변환기는 리튬전지의 충방전 특성을 고려하여 설계하였으며, 충전모드에서는 포워드 변환기로 동작하고 방전모드에서는 절연된 부스트 변환기로 동작한다. 해석을 바탕으로 설계조건에 부합하는 변압기의 권선 수, 인덕터, 커패시터 및 스위칭 소자를 설계하였다. 끝으로 설계한 변수를 적용한 시뮬레이션과 실험을 통하여 본 논문에서 제안한 변환기 설계의 타당성을 입증하였다.

• 대한안전경영과학회지
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• 제2권2호
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• pp.187-200
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• 2000

The charge and discharge current in EPR(Ethylene Propylene Rubber), which were irradiated with the radiant capacity of 0~600 ［kgy/h］, have been measured in order to investigate the influence of the atmosphere (oxygen, air and vacuum) on electrical properties. It has been shown that the charge and discharge current increase as the amount of radiant capacity increases in air and vacuum atmosphere. This electrical property degradation can be speculated due to that the C＝O radicals or impurities, which comes from during shaping process, may act as dipoles. On the other hand, the charge and discharge current are shown to be higher in the amount of 1［kgy/h］ than these in 10［kgy/h］ in air atmosphere, because the charge and discharge current can be increased as the exposure time is extended with slower rate. Under the same amount of irradiation, the charge and discharge current in oxygen atmosphere are shown to be higher than those in vacuum. This is possibly due to that the main chain can be broken by oxidation when it is exposed to the $\gamma$ -rays.

• 한국전자통신학회논문지
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• 제10권12호
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• pp.1337-1344
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• 2015

Li-ion 배터리를 생산하는데 있어서 충/방전을 통한 formation 과정이 필요하다. 이 과정에서 방전기의 부하 저항을 통해 방전하게 되는데 이때 에너지 손실이 발생한다. 따라서 본 논문에서는 DC ${\mu}-Grid$ 기반의 충/방전 시스템에서 배터리를 효율적으로 운영하는 방안에 대해 연구하였다. 컴퓨터 시뮬레이션 결과, DC ${\mu}-Grid$ 기반의 충/방전 시스템에서 충전 배터리 set 3개 기준 대비 방전 배터리 set의 수가 133%를 초과하게 되면 망 전압이 안정화되는 과정에서 발생하는 전압 fluctuation 폭을 초과하기 때문에 시스템에 치명적인 손상을 야기한다. 따라서 충전 배터리 set 3개 기준 대비 방전 배터리 set의 수를 133%까지 운영할 수 있으며 획기적인 에너지 절감 효과를 확인할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.968-970
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• 1999

The trend of increasing of portable electric devices and demand for global environmental conservation have demands the development of high energy density rechargeable batteries. Lithium polymer battery has excellent theoretical energy density and energy conversion efficiency. Lithium polymer battery, included solid polymer electrolyte(SPE), can be viewed as a system suitable for wide applications from thin film batteries for microelectronics to electric vehicle batteries. The purpose of this paper is to research and development of flyash anode for lithium polymer battery. We investigated AC impedance response and charge/discharge characteristics of flyash/SPE/Li cells. The radius of semicircle associated with the interfacial resistance of flyash/SPE/Li cell increased very slowly during discharge process from 3.11V to 0.478V. And then the cell resistance was decreased at discharge process from 10% SOC to 0% SOC. Also, The radius of semicircle associated with the interfacial resistance of flyash/SPE/Li cell decreasing very slowly during charge process. And then the cell resistance was increased after 20th discharge precess. The discharge capacity based on flyash of 1st and 20th cycles was 276mAh/g and 143mAh/g.

• 전기화학회지
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• 제1권1호
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• pp.8-13
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• 1998

This work presents the way how to evaluate the degree of reversibility of the discharging process undergone by the nickel hydroxide film cathodically deposited on pure nickel as a positive electrode for electrochemical capacitor using the combined cyclic voltammetry and potential drop method, supplemented by galvanostatic discharge and open-circuit potential transient methods. The time interval necessary just to establish the current reversal of anodic to cathodic direction from the moment just after applying the potential inversion of anodic to cathodic direction, was obtained on cyclic voltammogram. The cathodic charge density passed upon dropping the applied potential, was calculated on potentiostatic current density-time curve. Both the time interval and the cathodic charge density in magnitude can be regarded as being measures of the degree of reversibility of the discharging process undergone by the positive active material for supercapacitor, i.e. , the longer the time interval is, the lower is the degree of reversibility and the greater the cathodic charge density is, the higher is the degree of reversibility. From the applied potential dependences of the time interval and cathodic charge density, discharge at $0.42 V_{SCE}$ was determined to be the most reversible.

• 한국수소및신에너지학회논문집
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• 제8권1호
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• pp.31-41
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• 1997

In order to investigate the mechanism of electrochemical hydrogenation reaction on Zr-based Laves phase hydrogen storage alloy electrodes, electrochemical charge/discharge characteristics, potentiostatic/dynamic polarizations and electrocehmical impedance spectroscopy(EIS) of Zr-Ti-Mn-Ni and Zr-Ti-Mn-Ni-M(M=Fe, Co, Al) alloys were examined. Electrochemical discharge capacities of the alloys were quite different with gas charge capacities. Therefore, it was considered that discharge capacities of the alloys depend on electrochemical kinetic factors rather then thermodynamic ones. Discharge efficiencies were increased linearly with exchange current densities. The results of potentiostatic/dynamic polarization measurements showed that electrochemical charge and discharge reaction of Zr-based Laves phase hydrogen storage alloys is controlled by charge transfer process at the electrode surface. The EIS measurements also confirmed this result.