• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.5-10
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• 2019

In this study, electrochemical characteristics of artificial graphite coated with petroleum pitch using solvent method as anode material of lithium ion battery were investigated. As the solvent, n-hexane, toluene, tetrahydrofuran and quinoline were used. The surface of the prepared anode material was analyzed by SEM and TEM. Also the electrochemical performances of the prepared anode materials were performed by constant current first charge/discharge, cycle, cyclic voltammetry and impedance tests in the electrolyte of $LiPF_6$ dissolved inorganic solvents (EC:DEC=1:1 vol%). The coating thickness of the prepared graphite was about 100-500 nm and the graphite coated with THF solvent had a smoother surface than that using other solvents. It was found that pitch-coated graphite (THF) show the low initial irreversible capacity (51 mAh/g), the high discharge capacity (360 mAh/g) and coulombic efficiency (99%).

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.672-678
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• 2019

The electrochemical properties of pitch-coated natural graphite(NG) were investigated as an anode for lithium-ion batteries. The anode materials were prepared by heat-treatment of mixture of NG and petroleum pitch at $1000^{\circ}C$. The pitches with various softening points were used as carbon precursor. The physical properties of anode materials were analyzed by TGA, SEM, PSA and BET. As the softening point increased, the thickness of the coating layer increased and the specific surface area decreased. The electrochemical performances were investigated by initial charge/discharge efficiency, cycle stability, cyclic voltammetry, rate performance and electrochemical impedance spectroscopy. The carbon-coated NG using pitch with softening points of $250^{\circ}C$ showed an initial discharge capacity of 361 mAh/g and a coulombic efficiency of 92.6%. Also, the rate performance(5 C/0.2 C) was 1.6 times higher than that of NG, and it had a capacity retention (90%) after 50 cycles at 0.5 C.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.338-344
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• 2022

It is necessarily required in developing Si-based anode materials for lithium ion batteries, and the related researches are actively working especially in Si-carbon composite material. On the other hand, the photovoltaic and semiconductor industries discard huge amount of Si resources, facing the environmental issue. In this study, recycled Si resource is adopted to obtain Si-carbon composite for LIB(Lithium-Ion Batteries). In order to improve high-capacity retention characteristics and cycle stability of a Si anode material for the LIB, two differenct composites having a mass ratio of silicon and pitch of 1:1 and 2:1 are synthesized and electrochemical characteristics of the anode material manufactured by simple self-assembly method. This result in excellent initial capacity with stable cycle life, and confirming the potential use of recycled Si material for LIB.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.85-94
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• 2011

Expanded graphites were used as anode materials of high power Li-ion secondary battery. The expanded graphite was prepared by mixing the graphite with $HClO_4$ as a intercalation agents and $KMnO_4$ as a oxidizing agents. The physical and electrochemical properties of prepared expanded graphites through the variation of process variables such as contents of intercalation agent and oxidizing agent, and heat treatment temperature were analyzed for determination of optimal conditions as the anode of high power Li-ion secondary battery. After examing the electrochemical properties of expanded graphites at the different preparing conditions, the optimal conditions of expanded graphite were selected as 8 wt.% of oxidizing agent, 400 g of intercalation agent for 20 g of natural graphite, and heat treatment at $1000^{\circ}C$. The sample showed the improved charge/discharge characteristics such as 432 mAh/g of initial reversible capacity, 88% of discharge rate capability at 10 C-rate, and 24 mAh/g of charge capacity at 10 C-rate. However, the expanded graphite had the problems of potential plateaus like natural graphite and lower initial efficiency than the natural graphite.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.241-248
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• 2003

We controlled the amount of Y$_2$O$_3$additives, 8 mol% and 10 mol%, and the type of carbon pore former, activated carbon and carbon black, to improve the strength of porous NiO-YSZ anode materials for solid oxide fuel ceil. The 3-point flexural strength, porosity and electrical conductivity were evaluated. As a result, the strength of anode materials with the addition of carbon black was markedly improved. The strength of NiO-10 mol%YSZ sintered at relatively higher temperature was higher than that of NiO-8 mol%YSZ materials. The electrical conductivity of NiO-10 mol%YSZ with carbon black was evaluated as much as 10$^2$∼10$^3$S/cm at 700$^{\circ}C$∼1000$^{\circ}C$ in reducing atmosphere.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.326-332
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• 2021

In this study, a spherical carbon composite material containing nano-silicon was synthesized using hydrothermal synthesis, and coated with petroleum pitch to prepare an anode material to investigate the electrochemical characteristics. Hydrothermal synthesis was performed by varying molar concentration, and the pitch was coated using THF as an organic solvent to prepare a composite material. The physical properties of anode materials were analyzed using SEM, EDS, XRD and TGA, and the electrochemical performances were investigated by cycle, C-rate, cyclic voltammetry and electrochemical impedance tests in 1.0 M LiPF₆ electrolyte (EC : DMC : EMC = 1 : 1 : 1 vol%). The pitch-coated silicon/carbon composite (Pitch@Si/C-1.5) with sucrose of 1.5 M showed a spherical shape. In addition, a high initial capacity of 1756 mAh/g, a capacity retention ratio of 82% after 50 cycles, and an excellent rate characteristic of 81% at 2 C/0.1 C were confirmed.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.161-165
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• 2021

In general, SOFCs mainly use Ni-YSZ cermet, a mixture of Ni and YSZ, as an anode material, which is stable in a high-temperature reducing atmosphere. However, when SOFCs have operated at a high temperature for a long time, the structural change of Ni occurs and it results in the problem of reducing durability and efficiency. Accordingly, a development of a new anode material that can replace existing nickel and exhibits similar performance is in progress. In this study, SrTiO₃, which is a perovskite-based mixed conductor and one of the candidate materials, was used. In order to increase the electrical conduction properties, Y_0.08Sr_0.92Fe_0.3Ti_0.7O₃, doped with 0.08 mol of Y³⁺ in Sr-site and 0.03 mol of transition metal Fe³⁺ in Ti-site, was synthesized and its chemical diffusion coefficient and reaction constant were measured. Its electrical conductivity changes were also observed while changing the oxygen partial pressure at a constant temperature. The performance as a candidate electrode material was verified by predicting the defect area through the electrical conductivity pattern according to the oxygen partial pressure.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4441-4448
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• 2022

The electrochemical oxidation process has been widely studied in the field of wastewater treatment for the decomposition of organic materials through oxidation using ·OH generated on the anode. Pt anode electrodes with high durability and long-term operability have a low oxygen evolution potential, making them unsuitable for electrochemical oxidation processes. Therefore, to apply Pt electrodes that are suitable for long-term operation and large-scale processes, it is necessary to develop a new method for improving the decomposition rate of organic materials. This study introduces a method to improve the decomposition rate of organic materials when using a Pt anode electrode in the electrochemical oxidation process for the treatment of organic decontamination liquid waste. Electrochemical decomposition tests were performed using sodium dodecylbenzenesulfonate (SDBS) as a representative organic material and a Pt mesh as the anode electrode. Y₂O₃ particles were introduced into the electrolytic cell to improve the decomposition rate. The decomposition rate significantly improved from 21% to 99%, and the current efficiency also improved. These results can be applied to the electrochemical oxidation process without additional system modification to enhance the decomposition rate and current efficiency.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.243-247
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• 2014

Spherical NiO-YSZ particles were synthesized by ultrasonic spray pyrolysis (USP). The morphology of the synthesized particles can be modified by controlling parameters such as precursor pH, carrier-gas flow-rate, and temperature of the heating zone. The synthesized spherical NiO-YSZ particles have rough surface morphology at high carrier-gas flow-rates due to rapid gas exhaustion and insufficient particle ordering. The Ni-YSZ cermet anode synthesized by ultrasonic spray pyrolysis at a flow rate of l L/min, with precursor solution at pH4, showed a higher maximum power density of 256 $mW/cm^2$ compared to a conventionally mixed Ni-YSZ anode (185 $mW/cm^2$) at $800^{\circ}C$. While the area-specific resistance of conventionally mixed Ni-YSZ anodes increases gradually with operation time (indicating performance degradation), the Ni-YSZ anode synthesized by USP does not exhibit any performance degradation, even after 500 h.

• Journal of the Korean Chemical Society
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• v.67 no.6
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• pp.429-440
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• 2023

1,1-Dialkyl-2,5-bis(trimethylsilylethynyl)-3,4-diphenylsiloles (R=Et, i-Pr, n-Hex; 3a-c) were prepared and utilized as anode active materials for lithium-ion batteries; 3a was also used as a filler for the solid-state electrolytes (SSE). Siloles 3a-c were prepared by substitution reactions in which the two bromine groups of 1,1-dialkyl-2,5-dibromo-3,4-diphe- nylsiloles, used as precursors, were substituted with trimethylsilylacetylene in the presence of palladium chloride, copper iodide, and triphenylphosphine in diisopropylamine. Among siloles 3a-c, 3a had the best electrochemical properties as an anode material for lithium-ion batteries, including an initial capacity of 758 mAhg^-1 (0.1 A/g), which was reduced to 547 mAhg^-1 and then increased to 1,225 mAhg^-1 at 500 cycles. A 3a-composite polymer electrolyte (3a-CPE) was prepared using silole 3a as an additive at concentrations of 1, 2, 3, and 4 wt.%. The 2 wt.% 3a-CPE composite afforded an excellent ionic conductivity of 1.09 × 10^-3 Scm^-1 at 60℃, indicating that silole 3a has potential applicability as an anode active material for lithium-ion batteries, and can also be used as an additive for the SSE of lithium-ion batteries.