• 제목/요약/키워드: $Li_2O$

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Hydrothermal Synthesis of Li-Mn Spinel Nanoparticle from K-Birnessite and Its Electrochemical Characteristics (K-Birnessite를 이용한 Li-Mn Spinel 나노입자 합성 및 전기화학적 특성 평가)

  • Kim, Jun-Il;Lee, Jae-Won;Park, Sun-Min;Roh, Kwang-Chul;Sun, Yang-Kook
    • Applied Chemistry for Engineering
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    • v.21 no.5
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    • pp.590-592
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    • 2010
  • Li-Mn spinel ($LiMn_2O_4$) is prepared by a hydrothermal process with K-Birnessite ($KMnO_4{\cdot}yH_2O$) as a precursor. The K-Birnessite obtained via a hydrothermal process with potassium permanganate [$KMnO_4$] and urea [$CO(NH_2)_2$] as starting materials are converted to Li-Mn spinel nanoparticles reacting with LiOH. The molar ratio of LiOH/K-Birnessite is adjusted in order to find the effect of the ratio on the structural, morphological and electrochemical performances of the Li-Mn spinel. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetry (TG) are used to investigate the crystal structure and morphology of the samples. Galvanostatic charge and discharge are carried out to measure the capacity and rate capability of the Li-Mn spinel. The capacity shows a maximum value of $117\;mAhg^{-1}$ when the molar ratio of LiOH/K-Birnessite is 0.8 and decreases with the increase of the ratio. However the rate capability is improved with the increase of the ratio due to the reduction of the particle size.

Synthesis and Electrochemical Properties of $LiNi_{1-y-z}(M_1)_y(M_2)_zO_2$ for the Development of Cathode Materials with Large Capacity (고용량 양극재료 개발을 위한 $LiNi_{1-y-z}(M_1)_y(M_2)_zO_2$의 합성과 전기화학적 특성)

  • Song, Myoung-Youp
    • Journal of Hydrogen and New Energy
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    • v.18 no.3
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    • pp.325-333
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    • 2007
  • [ $LiNi_{0.995}Al_{0.005}O_2$ ], $LiNi_{0.990}Ti_{0.010}O_2$ and $LiNi_{0.0990}Al_{0.005}Ti_{0.005}O_2$ were synthesized with a combustion method by calcining in an $O_2$ stream at $750^{\circ}C$ for 36 h. The X-ray diffraction patterns of these synthesized samples showed $-NaFeO_2$ structure of rhombohedral system(space group; $R{\bar{3}}\;m$) with no evidence of impurities. Among these samples, $LiNi_{0.995}Al_{0.005}O_2$ exhibited comparatively high first discharge capacity and discharge capacity, and the best cycling performance. $LiNi_{0.995}Al_{0.005}O_2$ had the first discharge capacity of 165.2 mA h/g and a discharge capacity of 116.7 mA h/g at the 50th cycle at 0.1C rate. It showed the first discharge capacity of 141.0 mA h/g and a discharge capacity of 93.5 mA h/g at the 50th cycle at 0.5C rate.

Electrochemical Properties and Synthesis of $LiCoO_2$ Using Lithium Acetate Dihydrate and Cobalt(II) Acetate Tetrahydrate (Lithium Acetate Dihydrate와 Cobalt(II) Acetate Tetrahydrate로 합성한 $LiCoO_2$의 전기화학적 특성)

  • Ha, Kyung-Hwa;Jin, Bong-Soo;Doh, Chil-Hoon;Shim, Young-Jae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.515-515
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    • 2007
  • $LiCoO_2$ powder was synthesized by Sol-Gel method using inorganic materials. The starting materials, $CH_3COOLi^*2H_2O\;and\;Co(CH_3COO)_2{^*}4H_2O$, were mixed in the atomic ratio Li/Co of 1 and dissolved in i-propanol with acetic acid. The solution was dried for gelation, and finally obtained the pre-powder. The pre-powder were studied by thermal analysis. Based on the TGA result, heat treatment was performed at various temperature(500 to $800^{\circ}C$) for 2h in air atmosphere. The crystal structure, morphology, electrochemical property were carried out using XRD, SEM, cyclic voltammetry(CV).

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Li4SiO4 slurry conditions and sintering temperature for fabricating Li4SiO4 pebbles as tritium breeders for nuclear-fusion reactors

  • Young Ah Park;Ji Won Yoo;Yi-Hyun Park;Young Soo Yoon
    • Nuclear Engineering and Technology
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    • v.55 no.8
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    • pp.2966-2976
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    • 2023
  • A tritium breeder is a lithium-based material capable of producing tritium. Many researchers designing nuclear-fusion energy are studying tritium production using pebbles, which are solid-type breeders. The sphericity and size of the pebbles are critical in obtaining pebbles with good tritium-breeding efficiency. Furthermore, tritium-release efficiency can be increased by using pebbles with appropriate porosities. Promising raw materials for tritium-breeding materials include Li4SiO4 and Li2TiO3. Li4SiO4 has a higher lithium density than Li2TiO3 and exhibits excellent tritium-breeding efficiency. However, it has the disadvantage of being easily decomposed during the Li4SiO4-green-pebble sintering process because of its low structural stability at high temperatures and high lithium density. In this study, we attempted to determine the optimal conditions for manufacturing Li4SiO4 pebbles using the droplet-freeze-drying method. The optimal Li4SiO4 slurry conditions and sintering temperatures were determined. The optimal Li4SiO4 slurry-fabrication conditions were 3 wt% polyvinyl alcohol and 75 wt% Li4SiO4 based on the deionized-water weight content. The sintering temperature at which Li4SiO4 did not decompose and exhibited the optimum porosity of 10.8% was 900 ℃.

Up-conversion Property of Er2O3 and MgO Co-doped Stoichiometric LiNbO3 Single Crystal by Using the μ-PD Method (μ-PD법을 이용하여 성장시킨 Er2O3와 MgO를 첨가한 화학양론조성 LiNbO3 단결정의 Up-conversion 특성)

  • Shur, Joong-Won;Jeon, Won-Nam;Lee, Sung-Mun;Yang, Woo-Seok;Lee, Han-Young;Yoon, Dae-Ho
    • Journal of the Korean Ceramic Society
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    • v.39 no.9
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    • pp.835-839
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    • 2002
  • Stoichiometric $LiNbO_3$(LN) single crystals of 1 mm diameter and 30∼40 mm length with co-doped the $Er_2O_3$ and MgO were grown by the Micro-Pulling Down(${\mu}$-PD) method. The grown crystals were investigated for the change of the up-conversion property by the $Er_2O_3$ and MgO addition and the optical damage by the MgO concentration. Also, the crystals were studied the defects using the optical microscope and it is identified the homogeneities of the distribution of the $Er_2O_3$ and MgO concentration by the Electron Probe Micro Analysis(EPMA).

Enhanced Stability of LiCoO2 Cathodes in Lithium-ion Batteries Using Surface Modification by Atomic Layer Deposition

  • Jung, Yoon-S.;Cavanagh, Andrew S.;Dillon, Anne C.;Groner, Markus D.;George, Steven M.;Lee, Se-Hee
    • Journal of the Korean Ceramic Society
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    • v.47 no.1
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    • pp.61-65
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    • 2010
  • Ultrathin atomic layer deposition (ALD) coatings were found to enhance the performance of lithium-ion batteries (LIBs). Previous studies have demonstrated that $LiCoO_2$ cathode powders coated with metal oxides with thicknesses of $\sim100-1000{\AA}$ grown using wet chemical techniques improved LIB performance. In this study, $LiCoO_2$ powders were coated with conformal $Al_2O_3$ ALD films with thicknesses of only $\sim3-4{\AA}$ established using 2 ALD cycles. The coated $LiCoO_2$ powders exhibited a capacity retention of 89% after 120 charge-discharge cycles in the 3.3~4.5 V (vs. $Li/Li^+$) range. In contrast, the bare $LiCoO_2$ powders displayed only a 45% capacity retention. This dramatic improvement may result from the ultrathin $Al_2O_3$ ALD film acting to minimize Co dissolution or to reduce surface electrolyte reactions.

Characterization of LiNi1/3Co1/3Mn1/3O2 Cathode Materials Prepared from Different Precursors in Lithium Rechargeable Batteries (리튬2차전지에서 다른 전구체로부터 합성된 LiNi1/3Co1/3Mn1/3O2 양극 활물질의 특성)

  • Kim, Sung-Keun;Hong, Sung-Wan;Han, Kyeong-Sik;Lee, Hong-Ki;Shim, Joong-Pyo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.11
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    • pp.1029-1035
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    • 2008
  • $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ cathode materials prepared from different precursors in lithium rechargeable batteries were characterized by various analytical methods. $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ powders were synthesized by using solid-state reaction method and their physical and chemical properties were analyzed by XRD, SEM, particle size analyzer and TCP-AES. These materials showed different crystallinity, particle size, surface morphology and chemical composition. Also, the charge/discharge cycling of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ electrodes was carried out under various cut-off voltages and it showed different behaviors. It was found that the electrochemical cyclability of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ was strongly related to its crystallinity.

Investigation of Al modification as cationic dopants in Nirich LiNi0.91Co0.06Mn0.03O2 cathode

  • Ye-Wan Yoo;Seung-Hwan Lee
    • Journal of Ceramic Processing Research
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    • v.23 no.5
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    • pp.566-569
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    • 2022
  • In this paper, we have successfully prepared Al-doped Ni-rich LiNi0.91Co0.06Mn0.03O2 cathodes. The structural properties andelectrochemical performances are studied according to Al cationic doping. It can be confirmed that the crystallinity and cationdisordering of Ni-rich LiNi0.91Co0.06Mn0.03O2 were improved by Al doping. Based on such excellent structural quality, theelectrochemical performance of Al doping LiNi0.91Co0.06Mn0.03O2 was superior to that of pristine LiNi0.91Co0.06Mn0.03O2. The Aldoping Ni-rich NCM has an initial discharge capacity of 209.2 mAh g-1. In addition, it shows superior rate capability byshowing capacity retention of 58.5% under a high rate of 6.0 C. Therefore, it can be judged that Al doping LiNi0.91Co0.06Mn0.03O2can be applied to next-generation cathode for long-distance and fast-charging electric vehicles.

Microwave Dielectric Properties of the $(Na_{1/2}Sm_{1/2})TiO_3$ -$(Li_{1/2}Nd_{1/2})TiO_3$ Ceramics for mobile communication (이동통신용 $(Na_{1/2}Sm_{1/2})TiO_3$ -$(Li_{1/2}Nd_{1/2})TiO_3$ 세라믹스의 마이크로파 유전특성)

  • 윤중락;이헌용;김경용
    • Electrical & Electronic Materials
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    • v.10 no.9
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    • pp.901-908
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    • 1997
  • The microwave dielectric properties of (Na.$_{1}$2//Sm$_{1}$2/)TiO$_3$and (Li$_{1}$2//Nd$_{1}$2/)TiO$_3$ceramics were investigated. Dielectric constant quality factor and temperature coefficient of resonant frequency of (Li$_{1}$2//Nd$_{1}$2/)TiO$_3$ceramics sintered at 145$0^{\circ}C$ for 2 hours were 86.2, 2780(at 3.8GHz) and 215ppm/$^{\circ}C$respectively. The solid solution of X(Na.$_{1}$2//Sm$_{1}$2/)TiO$_3$-(1-X)(Li$_{1}$2//Nd$_{1}$2/)TiO$_3$increased delectric constant and quality factor were decreased. Whereas temperature coefficient of resonant frequency was optimized to zero at the composition of 0.6(Li$_{1}$2//Sm$_{1}$2/)TiO$_3$-0.4(Li$_{1}$2//Nd$_{1}$2/)TiO$_3$where dielectric constant and quality factor were 86.2, 95-(at 3.8GHz) respectively. Also band-pass filters made of this material were examined.

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