• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.1-11
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• 2012

Recently lithium ion secondary batteries (LIB) have rapidly developed because of their advantages such as high energy densities and capacities. Among them, an electrical vehicle which is the one of the environmental-friendly transportation facilities has been received a great attention, but, it is needed to overcome several obstacles of the LIB performances. LIB is practically adapted to Hybrid Electric Vehicle (HEV), but the issues for high capacities, long life time and safety should be solved. Moreover, LIBs still have some possibilities of explosion in the case of overheating of the used organic electrolyte and overcharging of the cell. Hence, it is urgently needed to replace the liquid electrolytes into the solid electrolytes due to the safety issues. Therefore, in this review, we summarized and discussed the research trends of the solid electrolyte to solve the concerns of safety and capacity of LIBs and published patents and articles.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.1
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• pp.46-52
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• 2003

유황 양 전극과 액체 전해질, 리튬 금속을 음극으로 사용한 리튬 유황 전지를 제조하여 그 특성을 조사하였다. 유황 전극은 유황파우더와 carbon black 을 도전재로, 그리고 바인더로 PVdF를 사용하여 제조하였다. 이렇게 제조된 셀은 두개의 다른 전압 구간에서 충방전 실험을 행하였다. 첫 번째 셀은 $S_8+{\chi}Li{\leftrightarrow}Li_2S_x(X=4{\sim}12)$ 반응만을 일어나 게 하기 위하여 2.1V 와 2.5V 사이에서, 그리고 두 번째 셀은 $Li_2S_x+{\chi}Li{\leftrightarrow}Li_2S(x=2{\sim}4)$의 반응만을 일어나게 하기 위하여 1.5V 와 2.5V 에서 충방전 하였다. 그 결과 첫 번째 셀이 더 좋은 싸이클 특성을 가지는 것을 확인 탈 수 있었다. 각 전압구간에서 각 셀이 충방전 되는 동안, 전해질 내로 녹아난 유황의 양은 큰 차치가 없는 것을 확인하였다. 그리고, 전압에 따른 전극의 임피던스를 측정한 결과, 방전이 끝난 후 큰 저항성분이 새로 생긴 것을 확인 할 수 있었다. 이는 사이클이 진행된 후의 전극표면을 SEM 분석을 행한 결과로부터 사이클이 진행된 후 전극 표면에 최종 반응 산물인 $Li_2S$ 가 피막형태로 형성된것을 확인 할 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.259-259
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• 2007

층상구조의 전이금속 산화물($LiMO_2$, M=Co, Ni, Mn)은 리튬이차전지용 양극재료로 활발한 연구가 진행되고 있다. 차세대 리튬이차전지 시스템의 개발 및 고성능화를 위해서는 전지의 용량을 결정하는 핵심 부품인 양극재료의 고용량화 및 고안정화는 필수 불가결하다. 따라서 본 연구에서는 상업적으로 큰 장점이 있는 고상반응 공정을 이용하여 리튬이차전지용 양극소재를 제조하고, 소재의 전기화학적, 구조적인 특성을 평가하였으며, 다음과 같은 주제를 가지고 연구를 진행하였다. $LiCoO_2$ 양극재료는 리튬이온전지로 널리 사용되고 있다. 높은 에너지 밀도의 리튬이온전지를 얻기 위해서는 $LiCoO_2$ 양극재료가 고용량화 및 고밀도화를 가져야 한다. 여기서 $LiCoO_2$ 분말이 irregular particle morphology를 가지면 tap density가 $2.2-2.4gcm^{-3}$로 에너지 밀도가 낮으나, 구형 $LiCoO_2$의 정극재료는 tap density가 $2.6-2.8gcm^{-3}$로 상대적으로 energy density가 높아지는 효과가 있다. 구형 $LiCoO_2$ 양극재료를 합성하기 위해서는 chelating agent를 이용한 "controlled crystallization" 침전법을 사용하여 합성한 구형 코발트 수화물을 사용하고 있다. "controlled crystallization" 침전법에서 사용되는 chelating agent로는 주로 ammonia가 이용되고 있다. 본 연구에서는 chelating agent로 ethylene diamine을 사용하여 sodium hydroxides를 precipitation으로 침전 반응하여 구형 코발트 수화물을 합성하였다. 상기 방법으로 합성된 코발트 수화물과 리튬 수화물($LiOH{\cdot}H_2O$-고순도화학(高殉道化學))을 사용하여 고상법을 통하여 $LiCoO_2$를 합성하였다. 제조된 분말의 결정구조와 전기화학적 특성분석은 X-선 회절분석 및 리트벨트 구조정산, 그리고 충/방전 싸이클링을 수행하였으며, 분말의 미세구조 변화를 SEM을 이용하여 분석하였다.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.101-106
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• 2016

In this study, we prepared an ionic liquid composite solid polymer electrolyte (PEO-LiTFSI-$Pyr_{14}TFSI$) with poly(ethylen oxide), lithium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide by blending-cross linking process. Although the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte displayed a small peak at 4.4 V, it had high electrochemical oxidation stability up to 5.7 V. Ionic conductivity of the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte increased with increasing temperature from $10^{-6}S\;cm^{-1}$ at $30^{\circ}C$ to $10^{-4}S\;cm^{-1}$ at $70^{\circ}C$. To investigate the electrochemical properties, the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte assembled with $LiFePO_4$ cathode and Li-metal anode. At 0.1 C-rate, the cell delivered $40mAh\;g^{-1}$ for $30^{\circ}C$, $69.8mAh\;g^{-1}$ for $40^{\circ}C$ and $113mAh\;g^{-1}$ for $50^{\circ}C$, respectively. The PEO-LiTFSI-$Pyr_{14}TFSI$ solid polymer electrolyte exhibited good charge-discharge performance in Li/SPE/$LiFePO_4$ cells at $50^{\circ}C$.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.435-438
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• 2009

A navigation aid buoy is a kind of safety facility for maritime navigation with a purpose of leading the vessels for navigating, docking and sail off. An advanced rechargeable battery is required for stable power supply for navigation aid buoy as the high magnitude LED lamps, real time location/control for navigation aids and e-Navigation support systems with maritime climate observation equipments have recently been deployed. This study is focused on the lithium battery, especially lithium polymer battery which is believed to be safer than the other types of batteries. The lithium polymer battery reviewed in this study is designed with $LiFePO_4$-based cathode, which has superior safety features to the oxide-based cathodes. Besides, a 3.6kWh battery pack has been built with the above-mentioned unit cells for the purpose of comparative research with lead acid battery system.

• Electronics and Telecommunications Trends
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• v.36 no.3
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• pp.76-86
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• 2021

Technologies for lithium secondary batteries are now increasingly expanding to simultaneously improve the safety and higher energy and power densities of large-scale battery systems, such as electric vehicles and smart-grid energy storage systems. Next-generation lithium batteries, such as lithium-sulfur (Li-S) and lithium-air (Li-O₂) batteries by adopting solid electrolytes and lithium metal anode, can be a solution for the requirements. In this analysis of battery technology trends, solid electrolytes, including polymer (organic), inorganic (oxides and sulfides), and their hybrid (composite) are focused to describe the electrochemical performance achievable by adopting optimal components and discussing the interfacial behaviors that occurred by the contact of different ingredients for safe and high-energy lithium secondary battery systems. As next-generation rechargeable lithium batteries, Li-S and Li-O₂ battery systems are briefly discussed coupling with the possible use of solid electrolytes. In addition, Electronics and Telecommunications Research Institutes achievements in the field of solid electrolytes for lithium rechargeable batteries are finally introduced.

• Journal of the Korean Electrochemical Society
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• v.5 no.3
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• pp.106-110
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• 2002

Gel-type polyacrylonitrile(PAN) polymer electrolytes have been prepared using ethylene carbonate(EC), propylene carbonate(PC) and dimethyl carbonate(DMC) plasticizer, $LiPF_6$ salt and $TiO_2$ ceramic filler. Electrochemical properties, such as electrochemical stability, ionic conductivity and compatibility with lithium metal and mechanical properly of polymer electrolytes were investigated. Charge/discharge performance of lithium secondary battery using these polymer electrolytes were investigated. The maximum load that the polymer electrolyte resists increased about two times as a result of adding $TiO_2$ in the polymer electrolyte containing EC and PC. Polymer electrolyte containing EC, PC and $TiO_2$ also showed ionic conductivity of $2\times10^{-3} S/cm$ at room temperature and electrochemical stability window up to 와 4.5V. Polymer electrolyte containing EC, PC, and $TiO_2$ showed the most stable interfacial resistance of $130\Omega$ during 20 days in the impedance spectra of the cells which were constructed by lithium metals as electrodes. Lithium metal secondary battery which employed $LiCoO_2$ cathode, lithium metal anode and $TiO_2$-dispersed polymer electrolyte showed $90\%$ of charge/discharge efficiency at the 1C rate of discharge.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.44-48
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• 2000

Amorphous $V_2O_5$ cathode thin films were prepared by DC-magnetron sputtering at room temperature and the thin film rechargeable lithium batteries were fabricated with the configuration of $V_2O_5/LIPON/Li$ using sequential ex-situ thin film deposition techniques. The electrochemical characteristics of $V_2O_5$ cathode materials Prepared at 80/20 of $Ar/O_2$ ratio showed high capacity and cycling behaviors by half cell test. LIPON solid electrolytes films were prepared by RF-magnetron sputtering using the self-made $Li_3PO_4$ target in pure $N_2$ atmosphere, and it was very stable for lithium contact in the range of 1.2-4.0 V vs. Li. Metallic lithium were deposited on LIPON electrolyte by thermal evaporation methode in dry room. Vanadium oxide based full cell system showed the initial discharge capacity of $150{\mu}A/cm^2{\mu}m$ in the range of $1.2\~3.5V$.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.36-39
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• 2018

Transparent olivine $LiNiPO_4$ thin films on sapphire substrates were fabricated by radio frequency (RF) magnetron sputtering. The X-ray diffraction patterns show these thin films have the phase of $LiNiPO_4$ with an ordered olivine structure indexed to the orthorhombic Pmna space group. $LiNiPO_4$ thin films deposited on sapphire substrates exhibit transmittance of about 83 %. It was confirmed that the $LiNiPO_4$ thin film exhibits a high potential of 5 V-class.

• Journal of the Korean Electrochemical Society
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• v.22 no.4
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• pp.139-147
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• 2019

Lithium-ion battery (LiB) with high energy density and efficiency has been utilized for the electric vehicle (EV) and energy storage system (ESS) as well as portable devices. However, as explosion accidents have frequently happened till lately, all-solid-state lithium secondary battery (ALSB) began to get in a spotlight because it can secure a very high safety and energy density by substituting flammable organic liquid electrolyte to nonflammable inorganic solid electrolyte. In spite of ALSB's certain merits, it has shown much poorer performance of cells than one of LiB due to some challenges, which have been small or never dealt with in the LiB system. Hence, although plenty of studies made progress to solve them, an approach about design of all-solid-state electrode (ASSE) has been limited on account of difficulty of ALSB's experiments. That is why the virtual 3D structure of an all-solid-state electrode has to be built and used for the prediction of cell performance. In this study, we elucidate how to form the 3D ASSE structure and what to be needed for the simulation of characteristics on ALSB. Furthermore, the ultimate orientation of 3D modeling and simulation for the study of ALSB are briefly suggested.