• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.362-363
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• 2008

Well-defined o-$LiMnO_2$ cathode materials were synthesized using LiOH and $Mn_3O_4$ starting materials at $1050^{\circ}C$ in an argon flow by quenching method. The synthesized $LiMnO_2$ particles with crystalline phases were identified with X-ray diffraction (XRD, Dmax/1200, Rigaku). XRD results, demonstrated that the compound $LiMnO_2$ can be indexed to a single-phase material having the orthorhombic structure. In this paper, we analyzed the electrochemical performance of $LiMnO_2$/Li using solid polymer electrolyte and liquid electrolyte.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.237-245
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• 2021

Atomic layer deposition (ALD) enhances the stability of cathode materials via surface modification. Previous studies have demonstrated that an Ni-rich cathode, such as LiNi_0.8Co_0.1Mn_0.1O₂, is a promising candidate owing to its high capacity, but is limited by poor cycle stability. In this study, to enhance the stability of the Ni-rich cathode, synthesized LiNi_0.8Co_0.1Mn_0.1O₂ was coated with Al₂O₃ using ALD. Thus, the surface-modified cathode exhibited enhanced stability by protecting the interface from Ni-O formation during the cycling process. The coated LiNi_0.8Co_0.1Mn_0.1O₂ exhibited a capacity of 176 mAh g^-1 at 1 C and retained up to 72% of the initial capacity after 100 cycles within a range of 2.8-4.3 V (vs Li/Li⁺. In contrast, pristine LiNi_0.8Co_0.1Mn_0.1O₂ presented only 58% of capacity retention after 100 cycles with an initial capacity of 173 mAh g^-1. Improved cyclability may be a result of the ALD coating, which physically protects the electrode by modifying the interface, and prevents degradation by resisting side reactions that result in capacity decay. The electrochemical impedance spectra and structural and morphological analysis performed using electron microscopy and X-ray techniques establish the surface enhancement resulting from the aforementioned strategy.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.306-311
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• 2016

Li-air batteries have received much attention due to their superior theoretical energy density. However, their sluggish kinetics on the cathode side is considered the main barrier to high performance. The rational design of electrode catalysts with high activity is therefore an important challenge. To solve this issue, we performed density functional theory (DFT) calculations to analyze the adsorption behavior of the $LiO_2$ molecule, which is considered to be a key intermediate in both the Li-oxygen reduction reaction (ORR) and the evolution reaction (OER). Specifically, to use the activity descriptor approach, the $LiO_2$ adsorption energy, which has previously been demonstrated to be a reliable descriptor of the cathode reaction in Li-air batteries, was calculated on $LaB_{1-x}B^{\prime}_xO_3$(001) (B, B' = Mn, Fe, Co, and Ni, x = 0.0, 0.5). Our fast screening results showed that $LaMnO_3$, $LaMn_{0.5}Fe_{0.5}O_3$, or $LaFeO_3$ would be good candidate catalysts. We believe that our results will provide a way to more efficiently develop new cathode materials for Li-air batteries.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.346-357
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• 2021

In recent years, supercapacitors have been developed rapidly as a rechargeable energy storage device. And the performance of supercapacitors is depending on electrode materials, the preparation method and performance of electrode materials have become the primary goal of scientific development. This study synthesizes Co₃O₄@MnO₂@PPy cathode material with porous pattern core-shell structure by hydrothermal method and electrodeposition. The result samples are characterized by X-ray diffraction transmission/scanning electron microscope, and X-ray photoelectron spectroscopy. Electrochemical evaluation reveals that electrochemical performance is significantly enhanced by PPy depositing. The specific capacitance of Co₃O₄@MnO₂@PPy is 977 F g^-1 at 1 A g^-1, the capacitance retention rate of 105%. Furthermore, the electrochemical performance of Co₃O₄@MnO₂@PPy//AC asymmetric supercapacitor assembles with AC as the negative electrode material is significantly better than that of MnO₂//AC and Co₃O₄@MnO₂//AC. The capacity of Co₃O₄@MnO₂@PPy//AC is 102.78 F g^-1. The capacity retention rate is still 120% for 5000 charge-discharge cycles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.318-319
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• 2005

본 연구에서는 $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ 혼합 정극활물질로 사용하여 전극을 제작하고 성능을 평가하였다. $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$와 $LiCoO_2$의 혼합비에 따른 충방전 거동 및 임피던스 변화를 측정하였다. 각 조성에서의 초기용량은 160 ~ 170 mAh/g 정도였으며, $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$의 첨가 비율이 증가함에 따라 비용량이 증가하였으나 고율에서의 방전용량은 낮았다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.650-654
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• 2006

[ $LiNi_{0.4}Mn_{0.3}Co_{0.3}O_2$ ] cathode material was synthesized by a mixed hydroxide method. Structural characterization was carried out using X-ray diffraction studies. Electrochemical studies were performed by assembling 2032 coin cells with lithium metal as an anode. DSC (Differential scanning calorimetry) data showed that exothermic reactions of $LiNi_{0.4}Mn_{0.3}Co_{0.3}O_2$ charged to 4.3 V versus Li started at high temperatures$(280\sim390^{\circ}C)$. The cell of $LiNi_{0.4}Mn_{0.3}Co_{0.3}O_2$ mixed cathode delivered a discharge capacity of 150 mAh/g at a 0.2 C rate. The capacity of the cell decreased with the current rate and a useful capacity of 134 mAh/g was obtained at a 2 C rate. The reversible capacity after 100th cycles was 126 mAh/g when a cell was cycled at a current rate of 0.5 C in $2.8\sim4.3V$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.18-22
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• 2001

Spinel $LiMn_{2-y}Mn_{y}O_4$ powder was prepared solid-state method by calcining the mixture of $LiOH{\cdot}H_2O$, $MnO_2$ and MgO at $800^{\circ}C$ for 36h. To investigate the effect of temperature for cycle behaviour of cathode material during cycling, charge-discharge experiments and initial impedance spectroscopy performed by the condition of the charge-discharge temperature. Initial charge-discharge capacity was gradually increased by rising charge-discharge temperature. However, capacity was suddenly decreased at high temperature during cycling. Capacity at low temperature was almost constant during cycling. It confirmed because Mn dissolution is more serious at high temperature than at low temperature.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.934-937
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• 1998

Charge/discharge property of LiMn2O4 was investigated with LiMn2O4/Li cell for use of lithium ion battery in electric vehicle. LiMn2O4 calcined at $800^{\circ}C$ for 36hr show high charge/discharge capacity and excellent cycle stability than that of others. This is found to be in agreement with expectation in the X-ray diffraction analysis. In addition, the kind and volume of conductive agent involved in LiMn2O4 cathode is excellent at super-s-black and 20wt%, respectively.

• 한국전기화학회:학술대회논문집
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• 1999.10a
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• pp.57-57
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• 1999

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.360-363
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• 2006

We synthesized $(La,\;Sr)MnO_{3+{\delta}$ as a cathode for SOFC by glycine nitrate process(GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3S/cm at $700^{\circ}C$ On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LnMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,\;Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4hrs was 152.7s/cm at $700^{\circ}C$. The sintered $(La,\;Sr)MnO_3$ powder at $1000^{\circ}C$ for 4hrs got the deoxidization peak, depending on the temperature md in case of using nitrate solution as a start ing material the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,\;Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for m properly. And we found it to have different electrical conduct ivity the synthesized $(La,\;Sr)MnO_3$ powder by using different start ing materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.