• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.169-170
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• 2013

One important test for formation and grading of the lithium-ion battery is to confirm the performance of the battery while discharging battery down to zero volts. In this paper, a novel charge/discharge converter with zero-voltage discharge function is proposed. The proposed converter is able to discharge the battery until the voltage reaches to zero volts. The phase-shifted full bridge method is used to charge the battery and the current-fed push-pull method with bidirectional switches is used for the discharge. The ZVS turn-on is achieved in the charge operation and the ZVS turn-off in the discharge operation. The performance of the system is verified by the experiments using lithium-ion batteries.

• Applied Science and Convergence Technology
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• 제23권1호
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• pp.14-26
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• 2014

Copper is an important component from coin metal to electronic wire, integrated circuit, and to lithium battery. Copper oxides, mainly including $Cu_2O$ and CuO, are important semiconductors for the wide applications in solar cell, catalysis, lithium-ion battery, and sensor. Due to their low cost, low toxicity, and easy synthesis, copper oxides have received much research interest in recent year. Herein, we review the crystallization of copper oxides by designing various chemical reaction routes, for example, the synthesis of $Cu_2O$ by reduction route, the oxidation of copper to $Cu_2O$ or CuO, the chemical transformation of $Cu_2O$ to CuO, the chemical precipitation of CuO. In the designed reaction system, ligands, pH, inorganic ions, temperature were used to control both chemical reactions and the crystallization processes, which finally determined the phases, morphologies and sizes of copper oxides. Furthermore, copper oxides with different structures as electrode materials for lithium-ion batteries were also reviewed. This review presents a simple route to study the reaction-crystallization-performance relationship of Cu-based materials, which can be extended to other inorganic oxides.

• 공업화학
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• 제9권5호
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• pp.786-790
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• 1998

리튬이온이차전지에 사용되는 탄소부극의 성능을 향상시키기 위하여 새로운 탄소부극으로서 K-GIC를 합성하여 전기화학적 특성을 조사하였다. K의 삽입량은 KCl 수용액의 농도가 $2>3>1mole/{\ell}$의 순으로 증가하였으며 $1mole/{\ell}$의 KCl 수용액으로 처리하였을 때 K와 C의 mole 비는 156~388 carbon/potassium이었다. K-GIC의 합성조건을 $1mole/{\ell}$ KCl 수용액으로 $700^{\circ}C$에서 1시간으로 처리하였을 때 가장 우수한 리튬의 삽입과 탈삽입 거동을 나타냈으며 가역성 또한 우수하였다.

• Journal of Electrochemical Science and Technology
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• 제12권4호
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• pp.424-430
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• 2021

The element iron (Fe) is affordable and abundantly available, and thus, it finds use in a wide range of applications. As regards its application in rechargeable lithium-ion batteries (LIBs), the electrochemical reactions of Fe must be clearly understood during battery charging and discharging with the LIB electrolyte. In this study, we conducted systematic electrochemical analyses under various voltage conditions to determine the voltage at which Fe corrosion begins in general lithium salts and organic solvents used in LIBs. During cyclic voltammetry (CV) experiments, we observed a large corrosion current above 4.0 V (vs. Li/Li⁺). When a constant voltage of 3.7 V (vs. Li/Li⁺), was applied, the current did not increase significantly at the beginning, similar to the CV scenario; on the other hand, at a voltage of 3.8 V (vs. Li/Li⁺), the current increased rapidly. The impact of this difference was visually confirmed via scanning electron microscopy and optical microscopy. Our X-ray photoelectron spectroscopy measurements showed that at 3.7 V, a thick organic solid electrolyte interphase (SEI) was formed atop a thin fluoride SEI, which means that at ≥3.8 V, the SEI cannot prevent Fe corrosion. This result confirms that Fe corrosion begins at 3.7 V, beyond which Fe is easily corrodible.

• 한국안전학회지
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• 제36권5호
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• pp.1-9
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• 2021

With the convergence of the information and communication technologies, a new age of technological civilization has arrived. This is the age of intelligent revolution, known as the 4th industrial revolution. The 4th industrial revolution is based on technological innovations, such as robots, big data analysis, artificial intelligence, and unmanned transportation facilities. This revolution would interconnect all the people, things, and economy, and hence will lead to the expansion of the industry. A high-density, high-capacity energy technology is required to maintain this interconnection. As a next-generation energy source, lithium-ion batteries are in the spotlight today. However, lithium-ion batteries can cause thermal runaway and fire because of electrical, thermal, and mechanical abuse. In this study, thermal runaway was induced in 72.5 Ah NCM pouch-type lithium-ion batteries because of thermal abuse. The surface of the pouch-type lithium-ion batteries was heated by the hot plate heating method, and the effect of the rate of increase in the surface temperature on the thermal runaway trigger time was analyzed using Minitab 19, a statistical analysis program. The correlation analysis results confirmed that there existed a strong negative relationship between each variable, while the regression analysis demonstrated that the thermal runaway trigger time of lithium-ion batteries can be predicted from the rate of increase in their surface temperature.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권6호
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• pp.328-334
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• 2000

A lithium ion secondary battery using carbon as a negative electrode has been developed. Further improvements to increase the cell capacity are expected by modifying the structure of the carbonaceous material. There are hopes for the development of large capacity lithium ion secondary batteries with long cycle, high energy density, high power density, and high energy efficiency. In the present paper, needle cokes from petroleum were examined as an anode of lithium ion secondary battery. Petroleum cokes, MCL(Molten Caustic Leaching) treated in Korea Institute Energy Research, were carbonized at various temperatures of 0, 500, 700, $19700^{\circ}C$ at heating rate of $2^{\circ}C$/min for lh. The electrolyte was used lM liPF6 EC/DEC (1:1). The voltage range of charge & discharge was 0.0V(0.05V) ~ 2.0V. The treated petroleum coke at $700^{\circ}C$ had an initial capacity over 560mAh.g which beyond the theoretical maximum capacity, 372mAh/g for LiC6. This phenomena suggests that carbon materials with disordered structure had higher cell capacity than that the graphitic carbon materials.

• Journal of Electrochemical Science and Technology
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• 제3권1호
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• pp.14-23
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• 2012

Increasing demand of energy, the depletion of fossil fuel reserves, energy security and the climate change have forced us to look upon alternate energy resources. For today's electric vehicles that run on lithium-ion batteries, one of the biggest downsides is the limited range between recharging. Over the past several years, researchers have been working on lithium-air battery. These batteries could significantly increase the range of electric vehicles due to their high energy density, which could theoretically be equal to the energy density of gasoline. Li-air batteries are potentially viable ultra-high energy density chemical power sources, which could potentially offer specific energies up to 3000 $Whkg^{-1}$ being rechargeable. This paper provides a review on Lithium air battery as alternate energy resource for the future.

• 전기화학회지
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• 제18권4호
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• pp.161-171
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• 2015

수열합성법을 이용하여 $Zn_2GeO_4$ 및 $Zn_2SnO_4$ 나노선을 대량 합성하였고 리튬이온 전지와 소듐이온전지의 전기화학적 특성을 조사하였다. 리튬이온전지에서 $Zn_2GeO_4$ 나노선은 50 사이클 이후에 1021 mAh/g, $Zn_2SnO_4$ 나노선은 692 mAh/g의 높은 방전용량을 갖는 것을 확인하였고 두 나노선 모두 98%가 넘는 쿨롱 효율을 보였다. 따라서 이들 나노선은 고성능 리튬이온전지의 개발을 위한 음극소재로 기대된다. 또한 소듐이온전지에 대한 관심이 국내는 물론 전 세계적으로 집중이 되고 있어 처음으로 $Zn_2GeO_4$과 $Zn_2SnO_4$ 나노선에 대한 소듐이온전지를 제작하여 용량을 측정하였다. 측정한 결과 이들 나노선은 50 사이클 이후에 각각 168 mAh/g 과 200 mAh/g의 방전용량을 갖는 것을 확인하였고 두 나노선 모두 97%가 넘는 높은 쿨롱 효율을 보였으며 이에 우리의 첫 시도가 앞으로 많은 연구에 기여할 것으로 예상한다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 1998년도 전지기술 심포지움
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• pp.59-78
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• 1998

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.182-185
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• 2003

Lithium ion battery is required to balance cells in order to minimize the electric capacity difference between the batteries. This paper proposes a cell balancing method by using inductor. Simulation and experimental results are presented.