• 통합자연과학논문집
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• 제10권2호
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• pp.65-73
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• 2017

In this review paper, we will discuss about the methods of synthesizing Si nanowires by Top-down and Bottom-up. Silicon nanowires have a lot of application on various fields such as Li ion batteries, solar cells, chemical and biological sensors. We will address some of the applications of silicon Nanowires.

• 전기화학회지
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• 제22권3호
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• pp.128-137
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• 2019

리튬은 가장 가벼운 금속일 뿐만 아니라 낮은 환원전위(-3.04 V vs. SHE)와 큰 이론용량($3860mAh\;g^{-1}$)을 가지고 있어 차세대 음극 소재로 연구되고 있다. 리튬 금속을 전극으로 사용하는 리튬이차전지의 경우 전지의 효율과 에너지 밀도 극대화를 위해 얇은 두께의 리튬 전극이 필요하지만 기존의 리튬 박을 제조하는 물리적인 압연 방법으로는 일정수준 이하의 두께를 가지는 리튬 박을 제조하는데 한계가 있다. 본 연구에서는 물리적인 방법 대신 전해도금법으로 박막의 리튬을 전착하여 전해도금 시 사용되는 전해액의 종류와 전착 조건이 전착 특성 및 전착된 리튬의 전기화학 특성에 주는 영향을 확인하였다. 전착 전해액의 농도가 높을 수록 리튬 덴드라이트(dendrite) 형성 억제에 유리한 크고 둥근 형태의 리튬 입자를 형성하였으며 우수한 stripping 효율 (92.68%, 3M LiFSI in DME) 을 나타냈다. 전착 속도(전류 밀도)의 경우 속도 증가에 따라 리튬이 길이 방향으로 성장하여 길고 끝이 뾰족한 형태를 가지는 경향을 보였으며, 이로 인한 비표면적 증가로 전착된 리튬 전극의 stripping 효율이 감소(90.41%, 3M LiFSI in DME, $0.8mA\;cm^{-2}$)하는 경향을 확인하였다. 두 종류의 염과 용매를 조합하여 얻은 1.5M LiFSI + 1.5M LiTFSI in DME : DOL (1 : 1 vol%) (Du-Co) 전해액에서 전착된 리튬 전극이 가장 우수한 stripping 효율 (97.26%) 및 안정적인 가역성을 보였으며, 이는 염의 분해물로 구성된 전극 표면 피막의 Li-F 성분이 주는 안정성 향상과 피막의 유연성을 부여하는 DOL 효과에 기인한 것으로 추정된다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.767-767
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• 2004

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.429-429
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• 2008

Li$[Ni_{1/2}Co_{1/2}]O_2$ powder were synthesized from co-precipitation spherical metal oxide, $[Ni_{1/2}Co_{1/2}](OH)_2$. The preparation of metal hydroxide was significantly dependent on synthetic conditions, such as pH, amount of chelating agent, stirring speed, etc. The optimized condition resulted in $[Ni_{1/2}Co_{1/2}](OH)_2$, of which the particle size distribution was uniform and the particle shape was spherical, as observed by scanning electron microscopy. Calcination of the uniform metal hydroxide with LiOH at higher temperature led to a well-ordered layer-structured Li$[Ni_{1/2}Co_{1/2}]O_2$, as confirmed by X-ray diffraction pattern. Also these materials have ${\alpha}-NaFeO_2$ ($R\bar{3}m$) structure. Due to the homogeneity of the metal hydroxide, $[Ni_{1/2}Co_{1/2}](OH)_2$, the final product, Li$[Ni_{1/2}Co_{1/2}]O_2$, was also significantly uniform, i.e., the average particle size was of about 10 to 15 ${\mu}m$ in diameter and the distribution was relatively narrow. As a result, the corresponding tap-density was also high approximately 2.41 $gcm^{-3}$, of which the value is comparable to that of commercialized $LiCoO_2$.

• 자원리싸이클링
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• 제30권6호
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• pp.36-42
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• 2021

폐리튬이온배터리에 함유된 유가금속을 회수하기 위해 고온에서 용융환원처리한다. 용융환원된 금속상을 염산용액으로 침출한 다음 용매추출과 침전으로 유가금속을 분리한 여과액에는 니켈(II)과 미량의 규소(IV)가 함유되어 있다. 여액으로부터 고순도 니켈화합물을 회수하기 위해 흡착법에 의한 규소(IV)의 분리와 니켈(II)의 선택적 침전에 대해 조사했다. Polyacrylamide는 규소(IV)를 선택적으로 흡착했으나 용액의 점도 역시 증가하여 여과가 어렵다. 침전제로 탄산나트륨을 첨가하면 니켈(II)과 미량의 규소(IV)가 공침되었다. 반면 옥살산나트륨은 상온에서 니켈(II)만을 선택적으로 침전시켜 순도 99.99% 이상의 니켈옥살산염 결정상을 회수할 수 있었다.

• 자원리싸이클링
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• 제31권3호
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• pp.73-80
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• 2022

폐리튬이온전지를 고온에서 용융환원하면 금속혼합물을 얻을 수 있다. 금속혼합물을 황산이나 염산으로 침출한 다음 용매추출로 분리한 여액에는 니켈(II), 코발트(II), 망간(II)과 실리케이트(IV)가 함유되어 있다. 본 논문에서는 양이온교환수지인 Diphonix와 P204를 사용하여 황산과 염산 합성용액에 함유된 상기 이온들의 이온교환거동을 조사했다. 용액의 pH가 3인 황산용액에서 니켈(II), 코발트(II)와 망간(II)이 선택적으로 Diphonix에 흡착되었다. 용액의 pH가 6인 염산용액에서는 망간(II)이 P204수지에 선택적으로 흡착되어 분리가 가능했다. Diphonix와 P204에 흡착된 금속이온은 황산이나 염산용액으로 세출할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.714-720
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• 2003

Due to the electric power shortage in summer season and regulation of freon refrigerant, the application of gas absorption refrigeration and hot water systems are considerably increasing trend. But, this system consists of condenser, heat exchanger, supply pipe and radiator etc. which are easily corroded by acidity and dissolved oxygen and gases. In result, this system occurs scale attachment and corrosion damage like pitting and crevice corrosion. In this study, electrochemical polarization test of heat exchanger tubing material (copper, aluminium brass, 30% cupronickel(30% Cu-Ni)) was carried out in 60% lithium bromide solution at $95^{\circ}C$. As a result of polarization test, corrosion behavior by impressed potential and local corrosion. such as galvanic corrosion, pitting corrosion behavior, of tubing materials was investigated. The main results obtained are as follows: (1) The effect of pitting and crevice corrosion control of 30% cupronickel in 60% LiBr solution at $95^{\circ}C$ is very excellent. (2) Dissimilar metal corrosion of 30% cupronickel coupling to aluminium bronze is the most sensitive. (3) Current density behavior of tube materials by impressed potential is high in order of copper > aluminium brass > 30% cupronickel.

• 한국분말재료학회지
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• 제18권3호
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• pp.277-282
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• 2011

[ $LiCoO_2$ ] a cathode material for lithium rechargeable batteries, was prepared using recycled $Co_3O_4$. First, the cobalt hydroxide powders were separated from waste WC-Co hard metal with acid-base chemical treatment, and then the impurities were eliminated by centrifuge method. Subsequently, $Co_3O_4$ powders were prepared by thermal treatment of resulting $Co(OH)_2$. By adding a certain amount of $Li_2CO_3$ and $LiOH{\cdot}H_2O$, the $LiCoO_2$ was obtained by sintering for 10 h in air at $800^{\circ}C$. The synthesized $LiCoO_2$ particles were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analysis.

• 한국분말재료학회지
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• 제29권3호
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• pp.252-261
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• 2022

Cobalt is a vital metal in the modern society because of its applications in lithium-ion batteries, super alloys, hard metals, and catalysts. Further, cobalt is a representative rare metal and is the 30th most abundant element in the Earth's crust. This study reviews the current status of cobalt extraction and recycling processes, along with the trends in its production amount and use. Although cobalt occurs in a wide range of minerals, such as oxides and sulfides of copper and nickel ores, the amounts of cobalt in the minerals are too low to be extracted economically. The Democratic Republic of Congo (DRC) leads cobalt mining, and accounts for 68.9 % of the global cobalt reserves (142,000 tons in 2020). Cobalt is mainly extracted from copper-cobalt and nickel-cobalt concentrates and is occasionally extracted directly from the ore itself by hydro-, pyro-, and electro-metallurgical processes. These smelting methods are essential for developing new recycling processes to extract cobalt from secondary resources. Cobalt is mainly recycled from lithium-ion batteries, spent catalysts, and cobalt alloys. The recycling methods for cobalt also depend on the type of secondary cobalt resource. Major recycling methods from secondary resources are applied in pyro- and hydrometallurgical processes.

• Current Optics and Photonics
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• 제8권1호
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• pp.86-96
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• 2024

This research investigation employs a terahertz (THz) time-domain spectroscopy system to study the terahertz spectral characteristics of five different citrates in both solution and solid state. The citrates under examination are lithium citrate, monosodium citrate, disodium citrate, trisodium citrate, and potassium citrate. The results show that the THz absorption coefficients of the first four citrate solutions exhibit a decreasing trend with increasing concentration. However, the potassium citrate solution shows an opposite phenomenon. At the same time, the absorption coefficients of lithium citrate, trisodium citrate, and potassium citrate solutions are compared at the same concentration. The results indicate that the absorption coefficient of citrate solution increases in proportion to the increase of metal cation radius, which is explained from the perspective of the influence of metal cations on hydrogen bonds. In addition, we also study the absorption peaks of solid citrates, and characterize the formation mechanism of the absorption peaks by molecular dynamics simulations. This methodology can be further extended to the study of multitudinous salts, presenting theoretical foundations for the detection in food and medicine industries.