• 한국전기전자재료학회논문지
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• 제18권1호
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• pp.68-74
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• 2005

In this work, polymerization conditions of the gel polymer electrolyte (GPE) were studied to obtain better electrochemical performances in a lithium-ion polymer battery. When the polymerization temperature and time of the GPE were 70$^{\circ}C$ and 70 min, respectively, the lithium polymer battery showed excellent a rate capability and cycleability. The TMPETA (trimethylolpropane ethoxylate triacrylate)/TEGDMA (triethylene glycol dimethacrylate)-based cells prepared under optimized polymerization conditions showed excellent rate capability and low-temperature performances: The discharge capacity of cells at 2 Crate showed 92.1 % against 0.2C rate. The cell at -20 $^{\circ}C$ also delivered 82.4 % of the discharge capacity at room temperature.

• Journal of Electrochemical Science and Technology
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• 제13권3호
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• pp.323-338
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• 2022

Heat generation and temperature of a battery is usually presented by an equation of current. This means that we need to adopt time domain calculation to obtain thermal characteristics of the battery. To avoid the complicated calculations using time domain, 'state of charge (SOC)' can be used as an independent variable. A SOC based calculation method is elucidated through the comparison between the calculated results and experimental results together. Experiments are carried for rapid resistive discharge of a large-capacitive lithium secondary battery to evaluate variations of cell potential, current and temperature. Calculations are performed based on open-circuit cell potential (SOC,T), internal resistance (SOC,T) and entropy (SOC) with specific heat capacity.

• 한국융합학회논문지
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• 제12권4호
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• pp.1-8
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• 2021

현재 자동차를 포함한 에너지 저장장치 제품에는 리튬 이온 배터리가 주로 사용되고 있으며, 이를 과충전하거나, 고온 상황에 방치하는 잘못된 배터리 관리 상황 발생시 폭발 등 위험한 상황에 노출될 수 있으며, 과방전 시 배터리 불능 상황을 야기한다. 이로 인해 배터리 상태를 관리해주는 시스템이 필요하며 배터리 관리 시스템은 배터리 상태를 정확하게 인지하고 각 셀의 전압을 일정하게 유지하여 최적의 배터리 효율을 얻는 데 목적이 있다. 본 논문에서는 일반적 리튬이온배터리에 비해 고안전성을 갖는 리튬인산철 배터리팩과 이를 관리하기 위해 Matlab Simulink 기반의 시뮬레이션을 사용하여 셀 특성을 확인할 수 있는 RC등가회로 모델을 이용한 분석방법을 제시하고, 저전력 및 상호통신간섭이 적은 블루투스 기반 BMS 모듈의 알고리즘을 개발하였다.

• 한국전기전자재료학회논문지
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• 제11권9호
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• pp.727-732
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• 1998

Ag-deposited graphite powder was prepared by a chemical reduction method of metal particles onto graphite powder. X-ray diffraction observation of Ag-deposited graphite powder revealed that silver existed in a metallic state, but not in an oxidized one. From SEM measurement, ultrafine silver particles were highly dispersed on the surface of graphite particles. Cylindrical lithium ion secondary battery was manufactured using Ag-deposited graphite anodes and $LiCoO_2$ cathodes. The cycleability of lithium ion secondary battery using Ag-deposited graphite anodes was superior to that of original graphite powder. The improved cycleability may be due to both the reduction of electric resistance between electrodes and the highly durable Ag-graphite anode.

• 전력전자학회논문지
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• 제27권4호
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• pp.316-324
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• 2022

This paper uses seasonal auto-regressive integrated moving average (S-ARIMA), which is efficient in seasonality between time-series models, to predict the degradation tendency for lithium-ion batteries and study a method for improving the predictive performance. The proposed method analyzes the degradation tendency and extracted factors through an electrical characteristic experiment of lithium-ion batteries, and verifies whether time-series data are suitable for the S-ARIMA model through several statistical analysis techniques. Finally, prediction of battery aging is performed through S-ARIMA, and performance of the model is verified through error comparison of predictions through mean absolute error.

• 청정기술
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• 제18권3호
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• pp.320-324
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• 2012

본 연구에서는 리튬이온전지의 방전특성에 따른 열발생 속도를 계산하여 전지의 특성을 평가하였다. 이를 위하여 Butler-Volmer 식을 지배방정식으로 하여, 유사 2차원 모델링을 적용하고, 편미분 연산자인 FEMLAB을 이용하여 전산모사를 수행하였다. 전류밀도를 5 $A/m^2$에서 25 $A/m^2$까지 증가시켜 계산을 수행한 결과, 전류밀도가 증가함에 따라 전극표면에서 고체상 리튬의 소모량이 증가되는 것으로 나타났다. 이로 인한 확산제한의 발생시점이 단축되었으며, 동시에 리튬이온전지의 내부 전위가 컷오프 전위에 도달하는 시점에서 열발생 속도가 급격하게 증가되는 현상을 보여주었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 추계학술대회 논문집
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• pp.60-61
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• 2014

Lithium-Ion batteries have become the best tradeoff between energy, power density and cost of the energy storage system in many portable high electric power applications. In order to manage the battery efficiently State of Charge (SOC) of the battery needs to be estimated accurately. In this paper a model-based approach to estimate the SOC of the Lithium-Ion battery based on the estimation of the battery impedance is proposed. The validity and feasibility of the proposed algorithm is verified by the experimental results.

• Journal of Electrochemical Science and Technology
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• 제6권1호
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• pp.26-33
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• 2015

In this study, cell performance and thermal stability of lithium-ion cells with a polyimide (PI) separator are investigated. In comparison to conventional polyethylene (PE) separator, the PI separator exhibits distinct advantage in microporous structure, leading to superior reliability of the cell. The cells with PI separator exhibit good cell performances as same as the cells with PE separator, but their reliability was superior to the cell with PE separator. Especially in the hot-box test at 150 and 180℃, PI separator showed a contraction percentage close to 0% at 150℃, while the PE separator showed a contraction percentage greater than 10% in both width and length. Therefore, the PI separator can be the promising candidate for separators of the next generation of lithium-ion battery.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권2호
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• pp.129-140
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• 2013

As a fundamental experimental study for reliability improvement of lithium ion secondary battery, degradation mechanism was investigated by microscopic observation and acoustic emission monitoring. Microstructural observation of the decomposed battery after cycle test revealed mechanical and chemical damages such as interface delamination, microcrack of the electrodes, and solid electrolyte interphase (SEI). Acoustic emission (AE) signal was detected during charge and discharge of lithium ion battery to investigate relationships among cumulative count, discharge capacity, and microdamages. With increasing number of cycle, discharge capacity was decreased and AE cumulative count was observed to increase. Observed damages were attributed to sources of the detected AE signals.

• 통합자연과학논문집
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• 제10권3호
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• pp.171-174
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• 2017

Non-hydrolyzable fluorinated organosilicon compounds as an eletrolyte for the application of lithium-ion batteries (LIB) are synthesized. New synthetic method for the perfluorinated organosilicon compound containing spacer such as ethyl and propyl group with cyano moiety instead of ethylene glycol to prevent hydrolysis and to promote conductivity are developed in one pot reaction with moderately high yield. Air-sensitive boron trifluoride etherate is no longer required in this reaction. The products are characterized by spectroscopic analysis.