• Title/Summary/Keyword: $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$

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The Study on Structural Change and Improvement of Electrochemical Properties by Co-precipitation Condition of Li[Ni0.8Co0.15Al0.05]O2 Electrode (Li[Ni0.8Co0.15Al0.05]O2 전극의 공침 조건을 통한 구조적 변화와 전기적 특성의 향상 고찰)

  • Im, Jung-Bin;Son, Jong-Tae
    • Journal of the Korean Electrochemical Society
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    • v.14 no.2
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    • pp.98-103
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    • 2011
  • [ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.

Effect of MgF2 Surface Modification for LiNi0.8Co0.15Al0.05O2 Cathode Material on Improving Electrochemical Characteristics (LiNi0.8Co0.15Al0.05O2 양극활물질의 전기화학적 특성 향상을 위한 MgF2 표면처리 효과)

  • Jin, Su-Jin;Seo, Jin-Seong;Na, Byung-Ki
    • Korean Chemical Engineering Research
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    • v.58 no.1
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    • pp.52-58
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    • 2020
  • Electrochemical characterization and thermal stability were investigated for MgF2 coated LiNi0.8Co0.15Al0.05O2 cathode. The ratio of MgF2 was controlled by 0.5, 1, 3 wt%. Cyclic voltammetry, charge-discharge profiles, rate capability, cycle life were measured for electrochemical properties. DSC analysis was measured for thermal stability. The first discharge capacities of MgF2 coated LiNi0.8Co0.15Al0.05O2 were decreased at 0.1C-rate compared to pristine LiNi0.8Co0.15Al0.05O2. But the rate capability and cycle life of MgF2 coated LiNi0.8Co0.15Al0.05O2 were improved at 2C-rate. In DSC analysis result, the exothermic temperature of MgF2 coated LiNi0.8Co0.15Al0.05O2 was increased and peak height was decreased.

Electrochemical Properties and Thermal Stability of LiNi0.8Co0.15 Al0.05O2-LiFePO4 Mixed Cathode Materials for Lithium Secondary Batteries

  • Kim, Hyun-Ju;Jin, Bong-Soo;Doh, Chil-Hoon;Kim, Hyun-Soo
    • Journal of Electrochemical Science and Technology
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    • v.3 no.2
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    • pp.63-67
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    • 2012
  • We prepared various $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-cathode electrodes by changing the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ and $LiFePO_4$ used, and we analyzed the electrochemical characteristics of the cathodes. We found that the reversible specific capacity of the cathodes increased and that the capacity retention ratios of the cathodes decreased during cycling as the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ increased. Conversely, we found that although the reversible specific capacity of the cathodes decreased because of the material composition, the cycle property of the cathodes increased when the $LiFePO_4$ content increased. We analyzed the thermal stability of the $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-material cathodes by differential scanning calorimetry and found that it increased as the $LiFePO_4$ content increased.

Surface Modification of a Li[Ni0.8Co0.15Al0.05]O2 Cathode using Li2SiO3 Solid Electrolyte

  • Park, Jin Seo;Park, Yong Joon
    • Journal of Electrochemical Science and Technology
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    • v.8 no.2
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    • pp.101-106
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    • 2017
  • $Li_2SiO_3$ was used as a coating material to improve the electrochemical performance of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$. $Li_2SiO_3$ is not only a stable oxide but also an ionic conductor and can, therefore, facilitate the movement of lithium ions at the cathode/electrolyte interface. The surface of the $Li_2SiO_3$-coated $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ was covered with island-type $Li_2SiO_3$ particles, and the coating process did not affect the structural integrity of the $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ powder. The $Li_2SiO_3$ coating improved the discharge capacity and rate capability; moreover, the $Li_2SiO_3$-coated electrodes showed reduced impedance values. The surface of the lithium-ion battery cathode is typically attacked by the HF-containing electrolyte, which forms an undesired surface layer that hinders the movement of lithium ions and electrons. However, the $Li_2SiO_3$ coating layer can prevent the undesired side reactions between the cathode surface and the electrolyte, thus enhancing the rate capability and discharge capacity. The thermal stability of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ was also improved by the $Li_2SiO_3$ coating.

Effect of Calcination Temperature of Size Controlled Microstructure of LiNi0.8Co0.15Al0.05O2 Cathode for Rechargeable Lithium Battery

  • Park, Tae-Jun;Lim, Jung-Bin;Son, Jong-Tae
    • Bulletin of the Korean Chemical Society
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    • v.35 no.2
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    • pp.357-364
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    • 2014
  • Size controlled, $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ cathode powders were prepared by co-precipitation method followed by heat treatment at temperatures between 750 and $850^{\circ}C$. The synthesized samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance. The synthesized $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ has a good electrochemical performance with an initial discharge capacity of $190mAhg^{-1}$ and good capacity retention of 100% after 30 cycles at 0.1C ($17mAg^{-1}$). The capacity retention of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ is better than that at 800 and $850^{\circ}C$ without capacity loss at various high C rates. This is ascribed to the minimized cation disorder, a higher conductivity, and higher lithium ion diffusion coefficient ($D_{Li}$) observed in this material. In the differential scanning calorimetry DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by calcined at high temperature, and this decrease is especially at $850^{\circ}C$. This behavior implies that the high temperature calcinations of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ prevent phase transitions with the release of oxygen.

Surface-modified Li[Ni0.8Co0.15Al0.05]O2 Cathode Fabricated using Polyvinylidene Fluoride as a Novel Coating

  • Lee, Jun Won;Park, Yong Joon
    • Journal of Electrochemical Science and Technology
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    • v.7 no.4
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    • pp.263-268
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    • 2016
  • This study describes the effect of coating the $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ cathode surface with a homogeneous carbon layer produced by carbonization of polyvinylidene fluoride (PVDF) as a novel organic source. The phase integrity of the above cathode was not affected by the carbon coating, whereas its rate capability and cycling performance were enhanced. Similarly, the cathode thermal stability was also improved after coating, which additionally protected the cathode surface against the reactive electrolyte containing hydrofluoric acid (HF). The results show that coating the $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ cathode with carbon using the PVDF precursor is an effective approach to enhance its electrochemical properties.

The Effect of Surface Modification with La-M-O (M = Ni, Li) on Electrochemical Performances of Li[Ni0.8Co0.15Al0.05]O2 Cathode

  • Ryu, Jea-Hyeok;Kim, Seuk-Buom;Park, Yong-Joon
    • Bulletin of the Korean Chemical Society
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    • v.30 no.3
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    • pp.657-660
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    • 2009
  • The surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ cathode particle was modified by lanthanum based oxide to improve electrochemical property and thermal stability. The XRD pattern of surface layer was indexed with that of $La_4NiLiO_8$. The discharge capacity of modified electrode was higher than that of pristine sample, specially at fast charge-discharge rate and high cut-off voltage. In the DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by surface modification. Such enhancement may by attributed to the presence of stable lanthanum based oxide, which effectively suppressd the reaction between electrode and electrolyte on the surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ electrode.

Crystal Structure Changes of LiNi0.5Co0.2Mn0.3O2 Cathode Materials During the First Charge Investigated by in situ XRD

  • Lee, Sang-Woo;Jang, Dong-Hyuk;Yoon, Jeong-Bae;Cho, Yong-Hun;Lee, Yun-Sung;Kim, Do-Hoon;Kim, Woo-Seong;Yoon, Won-Sub
    • Journal of Electrochemical Science and Technology
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    • v.3 no.1
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    • pp.29-34
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    • 2012
  • The structural changes of $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material for lithium ion battery during the first charge was investigated in comparison with $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ using a synchrotron based in situ X-ray diffraction technique. The structural changes of these two cathode materials show similar trend during first charge: an expansion along the c-axis of the unit cell with contractions along the a- and b-axis during the early stage of charge and a major contraction along the c-axis with slight expansions along the a- and b-axis near the end of charge at high voltage limit. In $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode, however, the initial unit cell volume of H2 phase is bigger than that of H1 phase since the c-axis undergo large expansion while a- and b- axis shrink slightly. The change in the unit cell volume for $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ during charge is smaller than that of $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$. This smaller change in unit cell volume may give the $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material a better structural reversibility for a long cycling life.

A Surfactant-based Method for Carbon Coating of LiNi0.8Co0.15Al0.05O2 Cathode in Li Ion Batteries

  • Chung, Young-Min;Ryu, Seong-Hyeon;Ju, Jeong-Hun;Bak, Yu-Rim;Hwang, Moon-Jin;Kim, Ki-Won;Cho, Kwon-Koo;Ryu, Kwang-Sun
    • Bulletin of the Korean Chemical Society
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    • v.31 no.8
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    • pp.2304-2308
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    • 2010
  • A $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ (LNCAO/C) active material composite cathode was coated with carbon. The conductive carbon coating was obtained by addition of surfactant during synthesis. The addition of surfactant led to the formation of an amorphous carbon coating layer on the pristine LNCAO surface. The layer of carbon coating was clearly detected by FE-TEM analysis. In electrochemical performance, although the LNCAO/C showed similar capacity at low C-rate conditions, the rate capability was improved by the form of the carbon coating at high current discharge state. After 40 cycles of charge-discharge processes, the capacity retention of LNCAO/C was better than that of LNCAO. The carbon coating is effectively protected the surface structure of the pristine LNCAO during Li insertion-extraction.

Surface Coating and Electrochemical Properties of LiNi0.8Co0.15Al0.05O2 Polyaniline Composites as an Electrode for Li-ion Batteries

  • Chung, Young-Min;Ryu, Kwang-Sun
    • Bulletin of the Korean Chemical Society
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    • v.30 no.8
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    • pp.1733-1737
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    • 2009
  • A new cathode material based on Li$Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ (LNCA)/polyaniline (Pani) composite was prepared by in situ self-stabilized dispersion polymerization in the presence of LNCA. The materials were characterized by fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical properties including galvanostatic charge-discharge ability, cyclic voltammetry (CV), capacity, cycling performance, and AC impedance were measured. The synthesized LNCA/Pani had a similar particle size to LNCA and exhibited good electrochemical properties at a high C rate. Pani (the emeraldine salt form) interacts with metal-oxide particles to generate good connectivity. This material shows good reversibility for Li insertion in discharge cycles when used as the electrode of lithium ion batteries. Therefore, the Pani coating is beneficial for stabilizing the structure and reducing the resistance of the LNCA. In particular, the LNCA/Pani material has advantageous electrochemical properties.