• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.285-295
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• 2021

The inverse spinel Cobalt ferrite (CoFe₂O₄, CFO) is considered to be a promising alternative to commercial graphite anodes for lithium ion batteries (LIBs). However, the further development of CFO is limited by its unstable structure during battery cycling and low electrical conductivity. In an effort to address the challenge, we construct three-dimensional hierarchical flower-like CFO nanoclusters (CFO NCs)-decorated carbonized cotton carbon fiber (CFO NCs/CCF) composite. This structure is consisted of microfibers and nanoflower cluster composited of CFO nanoparticle, in which CCF can be used as a long-range conductive matrix, while flower-like CFO NCs can provide abundant active sites, large electrode/electrolyte interface, short lithium ion diffusion path, and alleviated structural stress. As anode materials in LIBs, the flower-like CFO NCs/CCF exhibits excellent electrochemical performance. After 100 cycles at a current density of 0.3 A g^-1, the CFO NCs/CCF delivers a discharge/charge capacity of 1008/990 mAh g^-1. Even at a high current density of 15 A g^-1, it still maintains a charge/discharge capacity of 362/361 mAh g^-1.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.11a
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• pp.103-106
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• 2003

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.25-28
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• 1998

Lithiated cobalt and nickel oxides are becoming very attractive as active cathode materials for secondary lithium ion secondary battery. $LiCoO_2$ is easily synthesized from lithium cobalt salts, but has a relatively high oxidizing potential on charge. LiNiOz is synthesized by a more complex procedure and its nonstoichiometry significantly degraded the charge-discharge characteristics. But $LiNiO_2$ has a lower charge potential which increases the system stability. Lithiated cobalt and nickel oxides are iso-structure which make the preparation of solid solutions of $LiNi_{1-x}Co_xO_2$ for O$LiCoO_2 and LiNiO_2$ electrode. The aim of the presentb paper is to study the electrochemical behaviour, as weU as the possibilities for practical application of layered Iithiated nickel oxide stabilized by $Co^{3+}$ substitution as active cathode materials in lithium ion secondary battery.

• Journal of Korean Society of Water and Wastewater
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• v.38 no.2
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• pp.95-107
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• 2024

This study proposes the use of a cobalt-based Prussian blue analogue (Co-PBA; potassium cobalt hexacyanoferrate), as an adsorbent for the cost-effective recovery of aqueous ammonium ions. The characterization of Co-PBA involved various techniques, including Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption analysis, and zeta potential. The prepared Co-PBA reached an adsorption equilibrium for ammonium ions within approximately 480 min, which involved both surface adsorption and subsequent diffusion into the interior. The isotherm experiment revealed a maximum adsorption capacity of 37.29 mg/g, with the Langmuir model indicating a predominance of chemical monolayer adsorption. Furthermore, the material consistently demonstrated adsorption efficiency across a range of pH conditions. Notably, adsorption was observed even when competing cations were present. Co-PBA emerges as a readily synthesized adsorbent, underscoring its efficacy in ammonium removal and selectivity toward ammonium.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.300-315
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• 2005

Recently plasma surface-cleaning or surface-etching techniques have been focused in the respect of decontamination of spent or used nuclear parts and equipment. In this study decontamination rate of metallic cobalt surface was experimentally investigated via its surface etching rate with a $CF_4-O_2$ mixed gas plasma and metallic surface wastes of cobalt oxides were simulated and decontaminated with $NF_3$ - Ar mixed gas plasma. Experimental results revealed that a mixed etchant gas with about $80{\%}\;CF_4-20{\%}\;O_2$ gives the highest reaction rate of cobalt disk and the rate reaches with a negative 300 DC bias voltage up to $0.43\;{\mu}m$/min at $380^{\circ}C$ and $20{\%}\;NF_3-80\%$ Ar mixed gas gives $0.2\;{\mu}m$/min of reaction rate of cobalt oxide film.

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.39-43
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• 2000

New coordination polymers of general form, $$[CoL_2X_2]_n$$ (L = 3,3'-oxybis(pyridine) (obp), 1,4-bis(3-pyri-doxy) benzene (bpob); X = Cl, NCS), have been prepared via a slow diffusion method. The reaction of the present linkers with cobalt(II) ion affords infinite 2-dimensional sheet products. For $[Co(obp) $_2Cl_2]_n$$, the local geometry of the cobalt center is an octahedral arrangement with four nitrogen donors and two chlorine ions in trans positions. $$[Co(bpob)_2(NCS)_2]_n$$ has provided a similar structure: the local geometry of the cobalt atom is an octahedral arrangement with four pyridine units and two NCS groups in transpositions. The obp and bpob linkers connect two cobalt(II) ions defining the edges of 40- and 60-membered $[Co(II)]_4$ ring, respectively. Thermal analyses of the coordination polymers show significant thermal behavior associated with the characteristic structures.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.627-636
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• 2022

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO₃ solutions using antimony oxide (Sb₂O₃) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca²⁺ or Ni²⁺ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co²⁺ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol^-1.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.736-740
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• 2008

The interaction of myelin basic protein (MBP) from bovine central nervous system with divalent calcium ion was studied by isothermal titration calorimetry at 27 ${^{\circ}C}$ in aqueous solution. The extended solvation model was used to reproduce the enthalpies of $Co^{2+}$-MBP interaction over the whole $Co^{2+}$ concentrations. The solvation parameters recovered from the solvation model were attributed to the structural change of MBP due to the metal ion interaction. It was found that there is a set of three identical and noninteracting binding sites for $Co^{2+}$ ions. The association equilibrium constant is 0.015 ${\mu}M^{-1}$. The molar enthalpy of binding is $\Delta$H = −14.60 kJ $mol^{-1}$.

• Journal of the Korean Vacuum Society
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• v.3 no.1
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• pp.130-137
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• 1994

SbSBr, BiSBr, SbSBr : Co, BiSBr : Co, SbSBr : Ni 및 BiSBr : Ni 단결정을 수직 Bridgman 방법으로 성장시켰다. 성장된 단결정의 구조는 orthorhombic 구조이며 광학적 energy band gap 구조는 간접적이형이었고 energy gap의 온도의존성은 일차 및 이차 상전이점에서 anomalous 한 특성이 나 타 났다. 불순물로 첨가한 cobalt와 nickel은 Td 대칭점에 Co2+ ion, Co3+ ion 및 Ni2+ ion으로 위치하며 이들 ion의 energy 준위간의 전자전이에 의하여 불순물 광흡수 peak들이 나타난다.

• Resources Recycling
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• v.11 no.3
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• pp.10-16
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• 2002

In the leaching of $LiCoO_2$with a strong acid such as sulfuric and nitric acid, an additional step was needed to recover cobalt and lithium separately from spent lithium ion batteries (LIBs). The leaching of $LiCoO_2$in an oxalic acid solution was investigated to recover cobalt selectively using a low solubility of cobalt oxalate at low pH. Leaching efficiency of 95% of lithium and less than 1% of cobalt were obtained when pure $LiCoO_2$powder was leached in 3M oxalic acid at $80^{\circ}C$ and 50 g/L pulpdensity. Under the above leaching conditions, complete dissolution of lithium was accomplished with mere 0.25% of cobalt in the solution when the cathodic active material collected from spent LIBs was employed. The lithium in the leaching solution can be recovered as a form of carbonate or hydroxide depending on the addition of $Na_2$$CO_3$or LiOH.