• 한국전기전자재료학회논문지
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• 제27권6호
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• pp.399-406
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• 2014

Thermal batteries are used for military power sources that require robustness and long storage life such as missiles and torpedoes. $FeS_2$ powder is currently used for cathode materials because of its high specific energy density, environmental non-toxicity and low cost. However, large particle size of conventional $FeS_2$ has been deterred its possible application for higher power thermal batteries. In order to improve the power density, high energy ball milling of $FeS_2$ has been introduced to crush the micron-sized $FeS_2$. Discharge characteristics of the single cells fabricated with nano-materials and conventional $FeS_2$ powder were evaluated.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.61-64
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• 2007

Ni/YSZ ($Y_{2}O_{3}-stabilized$ $ZrO_{2}$), Cu/YSZ and CuO/YSZ composite powder for a cathode material in high temperature electrolysis (HTE) was synthesized by a mechanical alloying method with Ni (or Cu, CuO, Co) and YSZ powder. Microstructure of the composite for HTE reaction has been analyzed with various techniques of XRD, SEM to investigate effects of fabrication conditions. And conductivity of electrode was measured, Cu/YSZ cermet showed the higher electrical conductivity value than Ni/YSZ.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1594-1597
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• 2008

Carbon nanotube (CNT) cathodes were fabricated using nano-sized silver powders as a bonding material. The effects of powder size on the field emission properties for the CNT cathode were investigated The better emission properties of CNT cathodes using smaller particles are due to a low sintering temperature of the bonding materials.

• 전기화학회지
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• 제5권2호
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• pp.74-78
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• 2002

아연공기전지는 공기중의 산소를 사용하므로 cathode의 재활용이 가능하다는 장점이 있으며 아연의 이론용량이 820(mAh/g)으로 상당히 높다. 그러나, 아연공기전지는 cathodf치 기공이 너무 작으면 외부로부터 유입되는 산소량이 부족하여 전지의 방전전압이 낮아지는 결과를 초래하게 되며 cathode에 포함되어 있는 도전재의 함량에 따라 저항 및 기공율에 많은 변화를 보이고 있다. 이에 본 연구에서는 전지의 용량, 출력특성, 방전전압, DC저항, ASTM에 의한 기공율 측정을 통해 도전재의 종류 및 함량이 아연공기전지에 미치는 영향을 연구하였으며, Super P의 도전재를 $5wt\%$ 첨가하였을 때 가장 우수한 전지특성을 얻을 수 있었다.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.447-452
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• 2008

We synthesized nano-sized $La_{1-x}Sr_xCoO_3$ ($x=0.1{\sim}0.4$) cathode catalyst for the zinc air secondary batteries by citrate method, And we measured the cathode's electrochemical characteristics according to content of strontium compose the cathode catalyst. We controlled the pH of precursor solution by 10 in the process of manufacturing the precursor, We heat treated the prepared precursor at various calcination temperature ($500{\sim}900^{\circ}C$), and examined the optimum calcinations temperature by XRD analysis and electrochemical evaluation. We examined the ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) performance of the prepared $La_{1-x}Sr_xCoO_3$ catalyst powder. When we consider ORR and OER performance simultaneously, $La_{0.7}Sr_{0.3}CoO_3$ catalyst has shown the best performance because of its lowest voltage deference between charge and discharge.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.455-458
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• 2001

Spinel $LiMn_{2-y}$$M_{y}$ $O_4$powder was prepared solid-state method by calcining the mixture of LiOH - $H_2O$, Mn $O_2$, ZnO and MgO at 80$0^{\circ}C$ for 36h. To investigate the effect of substitution with Mg, Zn cation, charge-discharge experiments and initial impedance spectroscopy performed. The structure of $LiMn_{2-y}$$M_{y}$ $O_4$crystallites was analyzed from powder X-ray diffraction data as a cubic spinel, space group Fd3m. all cathode material showed spinel phase based on cubic phase in X-ray diffraction. Ununiform which calculated by (111) face and (222) face was constant in spite of the change of y value, except PUf\ulcorner LiM $n_2$ $O_4$. The discharge capacities of the cathode for the cation subbstitUtes $LiMn_{2-y}$$M_{y}$ $O_4$/Li cell at the 1st cycle and at the 40th cycle were about 120~124 and 108~112mAh/g except LiM $n_{1.9}$Z $n_{0.1}$ $O_4$/Li cell, respectively. This cell capacity is retained by 93% after 40th cycle. AC impedance of $LiMn_{2-y}$$M_{y}$ $O_4$/Li cells revealed the similar resistance of about 65~110$\Omega$ before cycling. before cycling.g.g.

• 한국분말재료학회지
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• 제23권2호
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• pp.136-142
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• 2016

As precursors of cathode materials for lithium ion batteries, $Ni_{1/3}Co_{1/3}Mn_{1/3}(OH)_2$ powders are prepared in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH in the presence of $NH_4OH$ in air or nitrogen ambient. Calcination of the precursors with $Li_2CO_3$ for 8 h at $1,000^{\circ}C$ in air produces dense spherical cathode materials. The precursors and final powders are characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analysis, tap density measurement, and thermal gravimetric analysis. The precursor powders obtained in air or nitrogen ambient show XRD patterns identified as $Ni_{1/3}Co_{1/3}Mn_{1/3}(OH)_2$. Regardless of the atmosphere, the final powders exhibit the XRD patterns of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ (NCM). The precursor powders obtained in air have larger particle size and lower tap density than those obtained in nitrogen ambient. NCM powders show similar tendencies in terms of particle size and tap density. Electrochemical characterization is performed after fabricating a coin cell using NCM as the cathode and Li metal as the anode. The NCM powders from the precursors obtained in air and those from the precursors obtained in nitrogen have similar initial charge/discharge capacities and cycle life. In conclusion, the powders co-precipitated in air can be utilized as precursor materials, replacing those synthesized in the presence of nitrogen injection, which is the usual industrial practice.

• 한국분말재료학회지
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• 제30권6호
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• pp.516-520
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• 2023

Highly safe lithium-ion batteries (LIBs) are required for large-scale applications such as electrical vehicles and energy storage systems. A highly stable cathode is essential for the development of safe LIBs. LiFePO₄ is one of the most stable cathodes because of its stable structure and strong bonding between P and O. However, it has a lower energy density than lithium transition metal oxides. To investigate the high energy density of phosphate materials, vanadium phosphates were investigated. Vanadium enables multiple redox reactions as well as high redox potentials. LiVPO₄O has two redox reactions (V⁵⁺/V⁴⁺/V³⁺) but low electrochemical activity. In this study, LiVPO₄O is doped with fluorine to improve its electrochemical activity and increase its operational redox potential. With increasing fluorine content in LiVPO₄O_1-xF_x, the local vanadium structure changed as the vanadium oxidation state changed. In addition, the operating potential increased with increasing fluorine content. Thus, it was confirmed that fluorine doping leads to a strong inductive effect and high operating voltage, which helps improve the energy density of the cathode materials.

• 한국표면공학회지
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• 제57권1호
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• pp.22-30
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• 2024

This study reports a direct growth of carbon nanotubes (CNTs) on the surface of LiCoO₂ (LCO) powders to apply as highly efficient cathode materials in lithium-ion batteries (LIB). The CNT synthesis was performed using a thermal chemical vapor deposition apparatus with temperatures from 575 to 625 ℃. Ferritin molecules as growth catalyst of CNTs were mixed in deionized (DI) water with various concentrations from 0.05 to 1.0 mg/mL. Then, the LCO powders was dissolved in the ferritin solution at a ratio of 1g/mL. To obtain catalytic iron nanoparticles on the LCO surface, the LCO-ferritin suspension was dropped in silicon dioxide substrates and calcined under air at 550℃. Subsequently, the direct growth of CNTs on LCO powders was performed using a mixture of acetylene (10 sccm) and hydrogen (100 sccm) for 10 min. The growth behavior was characterized by scanning and transmission electron microscopy, Raman scattering spectroscopy, X-ray diffraction, and thermogravimetric analysis. The optimized condition yielding high structural quality and amount of CNTs was 600 ℃ and 0.5 mg/mL. The obtained materials will be developed as cathode materials in LIB.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1227-1228
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• 2006

The electrochemical properties of novel metal powders were investigated for the electrode materias of polymer electrolyte memebrane electrolysis. Two types of Pt black and $IrO_2$ powder electrodes were hot-pressed on the polymer electrolyte membrane to form membrane electrode assembly. The galvanodynamic polarization methode was used to characterize the electrochemical properties of both electrodes. From the experimental results, we concluded that the $IrO_2$ powder electrode exhibits better electrochemical performance than Pt black as cathode material for the electrolysis.