• Title/Summary/Keyword: Rechargeable lithium batteries

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$^7Li$ NMR studies of LiMn$_2$O$_4$ prepared by eutectic self-mixing method without any mixing

  • Lee, Youngil;Kyooseung Han;Hyunkoo Kang;Jaebum Choo
    • Proceedings of the Korean Magnetic Resonance Society Conference
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    • 2002.08a
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    • pp.85-85
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    • 2002
  • Lithiated transition metal oxides such as LiMn2O4, Lil-xMnO$_2$, LiNiO$_2$, LiCoO$_2$, and their solid solution phases are used as cathode materials for lithium rechargeable batteries. We prepared the cathode materials using a novel eutectic self-mixing method without any artificial mixing procedures. This method provides an extraordinarily simple way to make the cathode materials, and it is possible to prepare at very low temperature such as 25$0^{\circ}C$. Furthermore, the cathode materials produced have discharge capacities that are much better than cathode materials prepared by previously reported synthetic methods. The spontaneous and homogeneous mixing is verified by $^{7}$ Li magic-angle-spinning (MAS) NMR spectroscopy.

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Electrochemical Properties of Spinel $LiMn_2O_4$Synthesized at Various Sintering Condition (열처리 조건에 따른 스피넬 $LiMn_2O_4$의 전기 화학적 특성)

  • 한태희;박종광;한병성
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.12 no.1
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    • pp.50-55
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    • 1999
  • We have investigated the $LiMn_2O_4$system as an cathode material for lithium rechargeable batteries. $LiMn_2O_4$spinel oxides have been synthesized by a solid state methode. We varied sintering time at a fixed sintering temperature of 75$0^{\circ}C$. In order to investigate the electrochemical properties of prepared $LiMn_2O_4$we assembled three-electrode cells using the working electrode as active material and Li metal as the counter and reference electrodes. The electrolyte was 1 M LiPE$_{6}$-EC:DEC(1:1 by volume). The particle size of sample synthesized at 75$0^{\circ}C$ ranged about 60$\mu m$. The discharge capacity of a cell involving spinel $LiMn_2O_4$ increased with increasing sintering time.e.

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Research Trend of Solid Electrolyte for Lithium Rechargeable Batteries (리튬 이차전지용 고체전해질 개발 동향)

  • Suh, Soon-Sung;Yi, Cheol-Woo;Kim, Keon
    • 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.

Electrochemical Properties of LiMn2O4-LiNi1/3Mn1/3Co1/3O2 Cathode Materials in Lithium Secondary Batteries (리튬이차전지 양극활물질용 LiMn2O4-LiNi1/3Mn1/3Co1/3O2의 전기화학적 특성)

  • Kong, Ming Zhe;Nguyen, Van Hiep;Gu, Hal-Bon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.5
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    • pp.298-302
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    • 2016
  • In this work, $LiMn_2O_4$ and $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ cathode materials are mixed by some specific ratios to enhance the practical capacity, energy density and cycle performance of battery. At present, the most used cathode material in lithium ion batteries for EVs is spinel structure-type $LiMn_2O_4$. $LiMn_2O_4$ has advantages of high average voltage, excellent safety, environmental friendliness, and low cost. However, due to the low rechargeable capacity (120 mAh/g), it can not meet the requirement of high energy density for the EVs, resulting in limiting its development. The battery of $LiMn_2O_4-LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ (50:50 wt%) mixed cathode delivers a energy density of 483.5 mWh/g at a current rate of 1.0 C. The accumulated capacity from $1^{st}$ to 150th cycles was 18.1 Ah/g when the battery is cycled at a current rate of 1.0 C in voltage range of 3.2~4.3 V.

Cycling Performances of Lithium-Ion Polymer Cells Assembled with Surface-Modified Separators Containing Aluminum Fluoride (불화 알루미늄을 포함하는 표면 개질된 분리막으로부터 제조되는 리튬이온폴리머전지의 싸이클 특성에 관한 연구)

  • Eo, Seung-Min;Kim, Dong-Won
    • Journal of the Korean Electrochemical Society
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    • v.11 no.2
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    • pp.125-129
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    • 2008
  • Rechargeable lithium-ion polymer batteries have been considered to be next-generation power sources for portable electronic devices and electric vehicles. In this work, we tried to improve the cycling performances of lithium-ion polymer cells by coating aluminum fluoride and acrylonitrile-methyl methacrylate copolymer to the polyethylene separator. It was found that the addition of aluminum fluoride to the surface-modified separator reduced the interfacial resistances and thus the cell exhibited a less capacity fading and better high rate performance. The cell showed an initial discharge capacity of 150 mAh/g and good capacity retention at 0.5 C rate.

Electrochemical Characteristics of Ru Added Li4Ti5O12 as an Anode Material (Ru를 첨가한 음극활물질 Li4Ti5O12의 전기화학적 특성)

  • Cho, Woo-Ram;Na, Byung-Ki
    • Clean Technology
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    • v.20 no.4
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    • pp.433-438
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    • 2014
  • There is an increasing interest in the development of rechargeable batteries suitable for use in both hybrid electric vehicles and energy storage systems that require higher charge & discharge rates, bigger battery sizes and increased safety of the batteries. Spinel-type lithium titanium oxide ($Li_4Ti_5O_{12}$) as a potential anode for lithium ion batteries has many advantages. It is a zero-strain materials and it experiences no structural change during the charge/discharge precess. Thus, it has long cycle life due to its structural integrity. It also offers a stable operation voltage of approximately 1.55 V versus $Li^+/Li$, above the reduction potential of most organic electrolyte. In this study, Ru added $Li_4Ti_5O_{12}$ composites were synthesized by solid state process. The characteristics of active material were investigated with TGA-DTA, XRD, SEM and charge/discharge test. The capacity was reduced when Ru was added, however, the polarization decreased. The capacity rate of $Li_4Ti_5O_{12}$ with Ru (3%, 4%) addition was reduced during the charge/discharge precess with 10 C-rate as a high current density.

Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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Electrochemical Characteristics of $V_2O_5$ based All Solid State Thin Film Microbattery by Ex-situ Sputtering Method (Ex-situ 스퍼터링법에 의한 $V_2O_5$ 전 고상 박막전지의 전기화학적 특성)

  • Lim Y.C.;Nam S.C.;Jeon E.J.;Yoon Y.S.;Cho W.I.;Cho B.W.;Chun H.S.;Yun K.S.
    • 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 $1.2\~3.5V$.

Effect of Annealing Temperature on the Anode Properties of TiO2 Nanotubes for Rechargeable Lithium Batteries (열처리 온도에 따른 TiO2 나노튜브의 리튬이차전지 음전극 특성)

  • Choi, Min Gyu;Kang, Kun Young;Lee, Young-Gi;Kim, Kwang Man
    • Korean Chemical Engineering Research
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    • v.50 no.1
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    • pp.25-29
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    • 2012
  • $TiO_2$ nanotubes are prepared from rutile prticles via an alkaline hydrothermal synthesis and the consequent heat treatment at $300{\sim}500^{\circ}C$. The physical and electrochemical properties of the $TiO_2$ nanotubes are characterized for use as a anode material of rechargeable lithium battery. In particular, the microscale dusts as an impurity component occurred in the purification step after the hydrothermal reaction are completely removed to yield $TiO_2$ nanotube with a higher specific surface area and more obvious crystalline phases. As the annealing temperature increases, the specific surface area is slightly decreased due to some aggregation between the isotropically dispersed nanotubes. Highest initial discharge capacity of 250 mAh $g^{-1}$ is achieved for the $TiO_2$ nanotube annealed at $300^{\circ}C$, whereas the $400^{\circ}C$ $TiO_2$ nanotube shows the superior cycle performance and high-rate capability.

Synthesis and Structure of the Layered Cathode Material $Li[Li_xMn_{1-x-y}Cr_y]O_2$ for Rechargeable Lithium Batteries (리튬2차전지용 양극 소재 $Li[Li_xMn_{1-x-y}Cr_y]O_2$의 합성 및 층상구조 연구)

  • 최진범;박종완;이승원
    • Journal of the Mineralogical Society of Korea
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    • v.16 no.3
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    • pp.223-232
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    • 2003
  • The co-precipitation method is applied to synthesize the cathode material Li[L $i_{x}$M $n_{1-x-y}$C $r_{y}$ ] $O_2$ for lithium rechargeable batteries at $650^{\circ}C$ (CR650) and 8$50^{\circ}C$ (CR850), respectively. Rietveld indices indicate that $R_{wp}$ with respect to $R_{exp}$ ( $R_{wp}$/ $R_{exp}$) are 9.2%/10.1% for CR650 and 15.9%/9.76% for CR850, respectively. $R_{B}$ and S (GofF) shows 10.9%, 8.54% and 1.9, 1.6, respectively. Rietveld structure refinement reveals that layer structure of LiMn $O_2$ (R3m) coexists with lower symmetry of Li[L $i_{1}$3/M $n_{2}$3/] $O_2$ (C2/c) due to superlattice ordering of Li and Mn in metal-transition containing layers. Unit-cell parameters are calculated as a=2.8520(2)$\AA$, c=14.248(2)$\AA$, V=100.40(l)$\AA^3$ for CR650, and a=2.8504(1)$\AA$, c=14.2371(7)$\AA$, V=100.179(8)$\AA^3$ for CR850. Final chemistry is obtained as Li[L $i_{0.35}$M $n_{0.56}$C $r_{0.09}$] $O_2$ (CR650) and Li[L $i_{0.27}$M $n_{0.61}$C $r_{0.13}$] $O_2$ (CR850), respectively.y...y..vely.y...y..