• Clean Technology
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• v.29 no.2
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• pp.87-94
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• 2023

The recovery of valuable metals from waste lithium-based secondary batteries is very important in terms of efficiently utilizing earth's limited number of resources. Currently, the cathode material of a LiFePO₄ battery, a type of battery which is widely used in automobiles, contains approximately 5% lithium. After use, the lithium in these batteries can be used again as a raw material for new batteries through lithium recycling. In this study, low-concentration sulfuric acid, a commonly used type of inorganic acid, was used to selectively leach the lithium contained in a waste LiFePO₄ cathode material powder. In addition, in order to compare and analyze the leaching efficiency and separation efficiency of each component, the optimalleaching conditions were derived by applying a two-step leaching process with pulp density being used as a variable during leaching. When leaching with pulp density as a variable, it was confirmed that at a pulp density of 200 g/L, the separation efficiency was approximately 200 times higher than at other pulp densities because the iron and phosphorus components were hardly leached at this pulp density. Accordingly, the pulp density of 200 g/L was used tooptimize the leaching conditions for the selective leaching and recovery of lithium.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.601-602
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• 2013

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.571-576
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• 1998

This study was carried out for investigating the corrosion behaviors, corrosion mechanisms, and behaviors of elements on a separator for a molten carbonate fuel cell under both the electrolyte and anode side environment. A 310S austenitic stainless steel was used as the separator material. Corrosion proceeded via three steps; the formation step of corrosion product in which rapid corrosion takes place until stable corrosion product is formed after the beginning of corrosion, the protection step against corrosion until breakaway occurs after the formation step of stable corrosion product and the advancing step of corrosion after the breakaway. From the standpoint of the behavior of the elements in the specimen, Fe and Cr, Ni were enriched in the region of corrosion product, in the region of corrosion protection, and at the Cr-deplete zone, respectively. With respect to corrosion mechanism, ionization of electrolyte at the anode side was the main corrosion mechanism, and the final corrosion products were $LiFeO_2$ and $LiCrO_2$ at the anode side.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.4
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• pp.141-146
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• 2024

Energy Storage System(ESS) have been developed to store and efficiently utilize energy, transitioning from the traditional method of producing and consuming energy immediately via fossil fuels and generators. With the advancement of this technology, Battery Management System(BMS) that manage Li-ion batteries at the cell level play a crucial role in enhancing battery performance, lifespan, and safety. Among the BMS functions, cell balancing, which aligns the imbalanced voltages of cells, is essential for optimizing capacity in devices like ESS. It ensures all cells maintain the same voltage and capacity, improving performance and output stability. Therefore, this paper examines the operational characteristics of the cell balancing method within BMS when charging an imbalanced Li-ion battery.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.433-442
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• 1996

Electrochemical characteristics and physical properties of polymer electrolyte which immobilized lithium salts such as $LiClO_4$ and $LiCF_3SO_3$ and plasticizers such as ethylene carbonate(EC) and propylene carbonate(PC) in high molecular weight poly(ethylene oxide)[PEO] polymer was investigated. PEO-Li based polymer electrolyte with plasticizers showed ionic conductivity of $10^{-4}S/cm$ at room temperature and high electrochemical stability up to 4.5 V(vs. $Li^+/Li$), so it can be applied to lithium secondary battery. The crystallinity of PEO decreased with the addition of lithium salts and plasticizers, especially $LiClO_4$ and PC showed more effective than and $LiCF_3SO_3$ and EC. Glass transition temperature($T_g$) of polymer electrolyte increased with increasing lithium salt concentration whereas melting temperature ($T_m$) decreased. Polymer electrolyte with plasticizers crystallized at $6^{\circ}C$.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.541-547
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• 2011

Nanorod-clustered $MnO_2$ precursors with ${\alpha}$-, ${\beta}$-, and ${\gamma}$-phases are synthesized by hydrothermal reaction of $MnSO_45H_2O$ and $(NH_4)S_2O_8$. The formation of nanorod-clustered ${\beta}-MnO_2$ is particularly confirmed under the conditions of high reactant concentration and hydrothermal reaction at $150^{\circ}C$. The spinel $LiMn_2O_4$ nanorod-clusters are also prepared by lithiating the $MnO_2$ precursors, varying the concentration of lithiating agent ($LiC_3H_3O_2{\cdot}2H_2O$) and heat treatment temperature, and characterized for use as cathode material of lithium-ion batteries. As a result, the nanorod-clustered $LiMn_2O_4$ prepared from the ${\beta}-MnO_2$ at higher $LiC_3H_3O_2{\cdot}2H_2O$ concentration and the annealing at $800^{\circ}C$ is proven to show the cubic spinel structure and to achieve the high initial discharge capacity of 120 mAh/g.

• Polymer Science and Technology
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• v.21 no.2
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• pp.149-156
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• 2010

전기방사 탄소섬유와 s-VGCFs는 그 미세구조의 특성 때문에 응용분야가 서로 다르다. 전기방사 탄소나노섬유는 유기물을 섬유화하고 그것을 탄화하기 때문에 VGCFs에 비해서 낮은 가격에 대량생산이 가능하고 촉매를 사용하지 않기 때문에 전극으로 사용할 경우 금속불순물에 대한 부반응의 우려가 없다. 한편, 결정성이 낮고 세공이 잘 발달되어 비표면적이 크기 때문에 이온을 흡착해서 에너지를 저장하는 전기화학 캐패시터나 가스 흡착 분리나 촉매의 지지체로 사용하는데 장점이 있다. 이에 비해서 s-VFCFs는 섬유의 직경이 기존의 VGCF에 비해서 작으면서 잘 발달된 흑연구조가 동심원 구조를 하고 있어 굴곡강도가 크고 열 및 전기전도도가 우수하여 납축전지나 Li 이온전지의 충전제로 사용하여 역학적 특성과 향상시켜 주는 역할을 한다. 또한, 금속과 복합화하여 가벼우면서도 강도를 증가시켜주는 보강재로 사용가능하다.

• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.48-53
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• 2012

Polyethylene (PE) separator is the most popular separator for lithium-ion batteries. However, it suffers from thermal contraction and mechanical rupture. In order to improve the thermal/mechanical dimensional stabilities, this study investigated the effects of $Si_3N_4$ coating. SCS (Silicon-nitride Coated Separator) has been fabricated by applying 10 ${\mu}m$-thick $Si_3N_4$/PVdF coating on one side of PE separator. SCS exhibits enhanced thermal stability over $100{\sim}150^{\circ}C$: its thermal shrinkage is reduced by 10~20% compared with pristine PE separator. In addition, SCS shows higher tensile strength than PE separator. Employing SCS hardly affects the C-rate performance of $LiCoO_2$/Li coin-cell, even though its ionic conductivity is somewhat lower than that of PE separator.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.49-49
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• 1999

리튬 이차 전지를 박막화함으로써 개발된 고상의 마이크로 박막전지는 임의의 크기 및 형태로의 제작이 가능하며 액체전해질을 사용하지 않기 때문에 작동 중 열 또는 기체 생성물이 생기지 않아 높은 안정성을 갖으며 광범위한 사용 온도 범위를 가진다. 위와 같은 장점으로 인하여 충전 가능한 고상의 박막형 리튬 이차 전지는 점진적으로 그 사용 범위가 크게 확대될 것으로 판단된다. 즉, 초소형 전자, 전기 소자는 물론이며 조만간 실현될 스마트 카드, 셀루러폰 및 PCS와 같은 개인용 휴대 통신장비의 전력 공급계로의 응용이 가능할 것이다. 특히 장수명, 고에너지 밀도를 갖는 초소형의 전지를 필요로 하는 microelectronics, MEMS등에 이용될 수 있는 이차전지에 대한 요구가 점점 가시화 됨에 따라 박막공정을 이용한 이차전지개발기술이 요구되고 있으며, 박막제조기술을 이용한 고상의 박막형 및 전지에 관한 연구가 증가하고 있다. 본 연구에서는 박막형 리튬 이차전지의 Cathode 물질로써 비정질의 산화바나듐 박막을 반응성 스퍼터링에 의하여 상온에서 증착하였다. 박막형 이차전지의 여러 가지 Cathode 물질중 산화바나듐은 다른 물질들과는 달리 비정질 형태로 매우 우수한 충방전 특성을 나타낸다. 이런 특성으로 인해 다소 전지자체의 성능은 낮지만 저전력 저전압을 필요로 하는 초소형 전자 소자와 혼성되어 이용할 수 있는 잠재성이 매우 높은 물질이다. 바나듐 타겟의 경우 타겟 표면의 ageing에 따라 증착되는 박막의 특성이 매우 달라지게 되므로 presputtering의 시간을 변화시키면서 실험하였다. 또한 스퍼터링 중의 산소의 분압도 타겟의 ageing에 많은 영향을 주므로 실험 변수로 산소분압을 변화시키면서 실험하였다. 증착된 산화바나듐 박막의 표면은 scanning electron microscopy로 분석하였으며 구조 분석은 X-선 회절분석, X-ray photoelectron spectroscopy 그리고Auger electron spectroscope로 하였다. 증착된 산화바나듐 박막의 전기화학적 특성을 분석하기 위하여 리튬 메탈을 anode로 하고 EC:DMC=1:1, 1M LiPF6 액체 전해질을 사용한 Half-Cell를 구성하여 200회 이상의 정전류 충 방전 시험을 행하였다. Half-Cell test 결과 박막의 결정성과 표면상태에 따라 매우 다른 전지 특성을 나타내었다.

• Journal of the Korean Ceramic Society
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• v.42 no.9 s.280
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• pp.602-606
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• 2005

[ $LiCoO_{2}$ ] is the most common cathode electrode materials in Lithium-ion batteries. $LiCo_{0.97}Mg_{0.03}O_2$ was synthesized by the solid-state reaction method. We investigated crystal structures, electrical conductivities and electrochemical properties. The crystal structure of $LiCo_{0.97}Mg_{0.03}O_2$ was analyzed by X-ray powder diffraction and Rietveld refinement. The material showed a single phase of a layered structure with the space group R-3m. The lattice parameter(a, c) of $LiCo_{0.97}Mg_{0.03}O_2$ was larger than that of $LiCoO_2$. The electrical conductivity of sintered samples was measured by the Van der Pauw method. The electrical conductivities of $LiCoO_2$ and $LiCo_{0.97}Mg_{0.03}O_2$ were $2.11{\times}10^{-4}\;S/cm$ and $2.41{\times}10^{-1}\;S/cm$ at room temperature, respectively. On the basis of the Hall effect analysis, the increase in electrical conductivities of $LiCo_{0.97}Mg_{0.03}O_2$ is believed due to the increased carrier concentrations, while the carrier mobility was almost invariant. The electrochemical performance was investigated by coin cell test. $LiCo_{0.97}Mg_{0.03}O_2$ showed improved cycling performance as compared with $LiCoO_2$.