• Bulletin of the Korean Chemical Society
• /
• v.33 no.6
• /
• pp.1972-1978
• /
• 2012

The polymer of (2,2-dimethyl-1,3-propanediaminebis(salicylideneaminato))-nickel(II), Ni(saldMp), was deposited on multi-walled carbon nanotubes (MWCNTs) substrate by the route of potential linear sweep. The nano structures of poly[Ni(saldMp)] have been obtained by adjusting the monomer concentration of 0.1, 0.2, 0.5, 1.0 and 1.5 mmol $L^{-1}$. The poly[Ni(saldMp)] prepared in acetonitrile solution with monomer concentration of 1.0 mmol $L^{-1}$ shows the fastest growth rate. The effects of potential window on charge-discharge efficiency and electrodeposition scan number on capacitance performance were discussed. Poly[Ni(saldMp)] prepared with less electrodeposition scans exhibits higher capacitance, but this goes against the improvement of the whole electrode capacitance. Sample with 8 deposition scans is the best compromise with the geometric specific capacitance 3.53 times as high as that of pure MWCNTs, and 1.24 times for the gravimetric specific capacitance under the test potential window 0.0-1.0 V.

• Journal of Hydrogen and New Energy
• /
• v.27 no.1
• /
• pp.95-105
• /
• 2016

Spray-dried NiO-based oxygen carriers developed for chemical looping combustion required high calcination temperatures above $1300^{\circ}C$ to obtain high mechanical strength applicable to circulating fluidized-bed process. In this study, the effect of CBB ($CaO{\cdot}BaO{\cdot}B_2O_3$) addition, as a binder, on the physical properties and oxygen transfer reactivity of spray-dried NiO-based oxygen carriers was investigated. CBB addition resulted in several positive effects such as reduction of calcination temperature and increase in oxygen transfer capacity and porosity. However, oxygen transfer rate was considerably decreased. This was more apparent when a higher amount of CBB was added and MgO was added together. From the experimental results, it is concluded that CBB added NiO-based oxygen carriers are not suitable for chemical looping combustion and a new method to reduce calcination temperature while maintaining high oxygen transfer rate of NiO-based oxygen carriers should be found out.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 1995.11a
• /
• pp.25-25
• /
• 1995

Liquid phase sintering of 90W-6Ni-4Mn alloy has been investigated as functions of sintering atmosphere, heating rate, and reduction temperature. The present work accounts for the thermodynamic oxidatiodreduction reactions of constituent powders of W, Ni and Mn. By discounting these reactions, the previous investigations would obtain only the alloy with large pores and the lowered relative sintered density, by the liquid phase sintering under a dry hydrogen atmosphere. the sintering cycle consisted of a rapid heating to reduction temperatures under high purity nitrogen atmosphere, and holding for 4 hours and sintering at $1260^{\circ}C$ for 1 hour under a dry hydrogen gas. The relative density of the sintered alloy increased with increasing heating rate. As the reduction temperature increased, the relative density increased to the lm theotical density at the duction temture above $1150^{\circ}C$. The mimsturcatre of sintered alloys has been analysed by a scanning election microscope. The sintered density was compared with those obtained from the other investigators. It was found that the reduction $1150^{\circ}C$ results in the lowered densification of 90W-6Ni-4Mn alloy. This is caused by the fact that reducing reactions of W and Ni oxides contained in W an Ni powders concomitantly leads to oxidizing reaction of Mn powder the oxidized Mn is hardly reduced at sintering temperature and thereby remains large pores in the alloy. It is concluded that the W-Ni-Mn alloy with full density can be obtained by the precise control of atmosphere, heating rate, and sintering temperature.

• Journal of Magnetics
• /
• v.18 no.1
• /
• pp.34-38
• /
• 2013

This paper studies the effects of the Mn-site substitution by nickel on the magnetic properties and the magnetocaloric properties of $La_{0.7}Ca_{0.3}Mn_{1-x}Ni_xO_3$ (x = 0, 0.05 and 0.1). The orthorhombic crystal structures of the samples are confirmed by the room temperature X-ray diffraction. The dependence of the Curie temperature ($T_C$) and the magnetic entropy change (${\Delta}S_M$) on the Ni doping content was investigated. The samples with x = 0 had the first order phase transition, while the samples with x = 0.05 and 0.1 had the second order phase transition. As the concentration of Ni increased, the maximum entropy change (${\mid}{\Delta}S_M{\mid}_{max}$) decreased gradually, from 2.78 $J{\cdot}kg^{-1}{\cdot}K^{-1}$ (x = 0) to 1.02 $J{\cdot}kg^{-1}{\cdot}K^{-1}$ (x = 0.1), in a magnetic field change of 15 kOe. The measured value of $T_C$ was 185 K, 150 K and 145 K for x = 0, 0.05 and 0.1, respectively. The phase transition temperatures became wider as x increased. It indicates that the Mn-site substitution by Ni may be used to tailor the Curie temperature in $La_{0.7}Ca_{0.3}Mn_{1-x}Ni_xO_3$.

• Resources Recycling
• /
• v.30 no.6
• /
• pp.36-42
• /
• 2021

Spent lithium-ion batteries are treated by reduction-smelting at high temperatures to recover valuable metals. Solvent extraction and precipitation of the HCl leaching solution of reduction-smelted metallic alloys resulted in a filtrate containing Ni(II) and a small amount of Si(IV). Adsorption and precipitation experiments were conducted to recover pure Ni(II) compounds from the filtrate. Si(IV) was selectively loaded onto polyacrylamide, but this method did not efficiently filter the solution due to an increase in viscosity. The addition of Na₂CO₃ as a precipitant to the filtrate led to the simultaneous precipitation of Ni(II) and Si(IV). However, it was possible to recover nickel oxalate with a purity higher than 99.99% by selectively precipitating Ni(II) with the addition of Na₂C₂O₄ as a precipitant.

• KEPCO Journal on Electric Power and Energy
• /
• v.6 no.4
• /
• pp.461-466
• /
• 2020

There are many application fields of electrical energy storage such as load shifting, integration with renewables, frequency or voltage supports, and so on. Especially, the frequency regulation is needed to stabilize the electric power system, and there have to be more than 1 GW as power reserve in Korea. Ni-rich layered oxide cathode materials have been investigated as a cathode material for Li-ion batteries because of their higher discharge capacity and lower cost than lithium cobalt oxide. Nonetheless, most of them have been investigated using small coin cells, and therefore, there is a limit to understand the deterioration mode of Ni-rich layered oxides in commercial high energy Li-ion batteries. In this paper, the pouch-type 20 Ah-scale Li-ion full cells are fabricated using Ni-rich layered oxides as a cathode and graphite as an anode. Above all, two test conditions for the application of frequency regulation were established in order to examine the performances of cells. Then, the electrochemical performances of two types of Ni-rich layered oxides are compared, and the long-term performance and degradation mode of the cell using cathode material with high nickel contents among them were investigated in the frequency regulation conditions.

• Journal of Powder Materials
• /
• v.30 no.5
• /
• pp.387-393
• /
• 2023

Transition metal chalcogenides are promising cathode materials for next-generation battery systems, particularly sodium-ion batteries. Ni₃Co₆S₈-pitch-derived carbon composite microspheres with a yolk-shell structure (Ni₃Co₆S₈@C-YS) were synthesized through a three-step process: spray pyrolysis, pitch coating, and post-heat treatment process. Ni₃Co₆S₈@C-YS exhibited an impressive reversible capacity of 525.2 mA h g^-1 at a current density of 0.5 A g^-1 over 50 cycles when employed as an anode material for sodium-ion batteries. However, Ni₃Co₆S₈ yolk shell nanopowder (Ni₃Co₆S₈-YS) without pitch-derived carbon demonstrated a continuous decrease in capacity during charging and discharging. The superior sodium-ion storage properties of Ni₃Co₆S₈@C-YS were attributed to the pitch-derived carbon, which effectively adjusted the size and distribution of nanocrystals. The carbon-coated yolk-shell microspheres proposed here hold potential for various metal chalcogenide compounds and can be applied to various fields, including the energy storage field.

• Membrane Journal
• /
• v.34 no.2
• /
• pp.140-145
• /
• 2024

In modern times, when a change in the energy paradigm is required, hydrogen is an attractive energy source. Among these hydrogen purification technologies, technology using a membrane is attracted attention as a technology that can purify high purity hydrogen at low cost. However, palladium(Pd), which is mostly used because of its excellent hydrogen separation performance, is very expensive, so a replacement material is needed. In this study, a alloy membrane was manufactured from an alloy of niobium (Nb), which has high hydrogen permeability but is weak to hydrogen embrittlement, and nickel (Ni) and zirconium (Zr), which have low hydrogen permeability but are highly durable. Hydrogen permeation characteristics were confirmed under conditions of 350~450 ℃ at 1 to 4 bar. The maximum hydrogen permeation flux was 0.69 ml/cm²/min for the Ni₄₈Nb₃₂Zr₂₀ alloy membrane without Pd coating, and 13.05 ml/cm²/min for the Pd coated alloy membrane.

• Resources Recycling
• /
• v.17 no.1
• /
• pp.80-87
• /
• 2008

Cementation and solvent extraction processes were studied to separate nickel and iron ions from the $H_2SO_4$ leaching solution with 47 g/L $Fe(Fe^{2+}/Fe^{3+}=1.03),$, 23.5 g/L Ni and 0.90M $H_2SO_4$ which leached from Fe-Ni alloy. Iron powder was used as a reducing agent for the cementation of Ni ion from the leaching solution. The reduction percentage of Ni ion was $17{\sim}20%$ by adding 4 times stoichiometric amount of iron powder at $60{\sim}80$. This may result from the fact that the cementation of Ni ion occurred after the reduction of $Fe^{3+}$ to $Fe^{2+}$ and the neutralization of $H_2SO_4$ with iron powder. The cementation process was proved to be unfeasible for the separation/recovery of Ni ion from the leaching solution including $Fe^{3+}$ as a major component. $Fe^{2+}$ present in the leaching solution was converted to $Fe^{3+}$ for solvent extraction of Fe ion using D2EHPA in kerosene as a extractant. The oxidation of $Fe^{2+}$ to $Fe^{3+}$ was completed by the addition of 1.2 times stoichiometric amount of 35% $H_2SO_4$. 99.6% $Fe^{3+}$ was extracted from the leaching solution (23.5 g/L $Fe^{3+}$) by 4 stages cross-current extraction using 20 vol.% D2EHPA in kerosene. $NiSO_4$ solution with 98.5% purity was recovered from the $H_2SO_4$ leaching solution of scrapped Fe-Ni alloy.

• Journal of the Korean Electrochemical Society
• /
• v.24 no.4
• /
• pp.120-132
• /
• 2021

Although the development of high-Nickel is being actively carried out to solve the capacity limitation and the high price of raw cobalt due to the limitation of high voltage use of the existing LiCoO₂, the deterioration of the battery characteristics due to the decrease in structural stability and increase of the Ni content. It is an important cause of delaying commercialization. Therefore, in order to increase the high stability of the Ni-rich ternary cathod material LiNi_0.6Co_0.2Mn_0.2O₂, precursor Ni_0.6Co_0.2Mn_0.2-x(OH)₂/xTiO₂ was prepared using a nanosized TiO₂ suspension type source for uniform Ti substitution in the precursor. It was mixed with Li₂CO₃, and after heating, the cathode active material LiNi_0.6Co_0.2Mn_0.2-xTi_xO₂ was synthesized, and the physical properties according to the Ti content were compared. Through FE-SEM and EDS mapping analysis, it was confirmed that a positive electrode active material having a uniform particle size was prepared through Ti-substituted spherical precursor and Particle Size Analyzer and internal density and strength were increased, XRD structure analysis and ICP-MS quantitative analysis confirmed that the capacity was effectively maintained even when the Ti-substituted positive electrode active material was manufactured and charging and discharging were continued at high temperature and high voltage.