• Title/Summary/Keyword: Electrochemical study

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Electrochemical Characteristics of CFX Based Lithium Primary Batteries Produced by Carbon Fiber Reinforced Plastic -Derived Waste Carbon Fibers (탄소섬유강화플라스틱 유래 폐 탄소섬유로 제조된 불화탄소 기반 리튬일차전지의 전기화학적 특성)

  • Naeun Ha;Chaehun Lim;Seongmin Ha;Seongjae Myeong;Young-Seak Lee
    • Applied Chemistry for Engineering
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    • v.34 no.5
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    • pp.515-521
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    • 2023
  • In this study, waste carbon fiber obtained by pyrolysis of carbon fiber reinforced plastic (CFRP) was used to produce carbon fluoride through vapor phase fluorination and recycled as a reducing electrode material for lithium primary batteries. First, the physicochemical properties of the waste carbon fiber obtained by pyrolysis were determined, and the structural and chemical properties of carbon fluoride were analyzed to evaluate the effect of vapor phase fluorination on the waste carbon fiber. XRD analysis confirmed that the hexagonal network carbon laminated structure (002 peak) of the waste carbon fiber was gradually converted into a carbon fluoride structure (CFX, 001 peak) as the temperature of gas phase fluorination increased. The discharge capacity of the lithium primary battery produced using this carbon fluoride was up to 862 mAh/g. This was compared to the discharge capacity of carbon fluoride-based Li-ion batteries made of other carbon materials. These results suggest that carbon fluoride made from waste CFRP-based carbon fibers can be used as a reducing electrode material for Li-ion batteries.

Effects of Mo co-doping into Fe doped β-Ni(OH)2 microcrystals for oxygen evolution reactions (Fe-doped β-Ni(OH)2의 산소발생반응 증가를 위한 Mo의 동시도핑효과)

  • Je Hong Park;Si Beom Yu;Tae Kwang An;Byeong Jun Kim;Jeong Ho Ryu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.34 no.1
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    • pp.30-35
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    • 2024
  • In order to improve the efficiency of the water splitting system for hydrogen production, the high overvoltage in the electrochemical reaction caused by the catalyst in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) must be reduced. Among them, transition metal-based compounds are attracting attention as catalyst materials that can replace precious metals such as platinum that are currently used. In this study, nickel foam, an inexpensive metal porous material, was used as a support, and Fe-doped β-Ni(OH)2 microcrystals were synthesized through a hydrothermal synthesis process. In addition, in order to improve OER properties, changes in the shape, crystal structure, and water splitting characteristics of Fe-Mo co-doped β-Ni(OH)2 microcrystals synthesized by co-doping with Mo were observed. The changes in the shape, crystal structure, and applicability as a catalyst for water splitting were examined.

Solid Electrolyte Composed of Poly(vinyl alcohol) and Oligo(3,4-ethylenedioxythiophene) Having a Crosslinked Structure (가교 구조를 갖는 poly(vinyl alcohol)과 oligo(3,4-ethylenedioxy-thiophene)으로 이루어진 고체 전해질)

  • Gyo Jun Song;Min Su Kim;Nam-Ju Jo
    • Applied Chemistry for Engineering
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    • v.35 no.4
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    • pp.303-308
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    • 2024
  • Currently, lithium secondary batteries have been used as medium- or large-sized energy sources such as electric vehicles and energy storage system (ESS) due to their high energy and eco-friendly characteristics. Currently commercialized lithium secondary batteries do not fully meet the demands for high energy density and safety. Many studies on solid electrolytes are being conducted to satisfy these requirements. In order to commercialize a solid electrolyte, it is important to supplement the low ion conductivity and high interface resistance with an electrode compared to the organic liquid electrolyte. Therefore, in this study, oligo(3,4-ethylenedioxythiophene (EDOT)) is added to poly(vinyl alcohol) (PVA), which is a polymer matrix with ion conductivity and sticky characteristics, to decrease the interfacial resistance with the same type of polythiophene (PTh)-based electrode. In addition, the addition of porous silicon dioxide (SiO2) filler improves lithium salt dissociation ability and increases ionic conductivity. And the electrochemical stability of the solid electrolyte, which has been lowered due to additives, is improved by introducing a cross-linked structure using boric acid (BA).

Effect of Pyrolysis Fuel Oil Based Carbon Coating onto CFX Cathode on High-rate Performance of Lithium Primary Batteries (불화탄소 전극의 열분해 연료유 기반 탄소 코팅이 리튬일차전지의 고율속 성능에 미치는 영향)

  • Sangyeop Lee;Naeun Ha;Seongjae Myeong;Chaehun Lim;Sei-Hyun Lee;Young-Seak Lee
    • Applied Chemistry for Engineering
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    • v.35 no.4
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    • pp.321-328
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    • 2024
  • The performance of carbon fluoride-based lithium primary batteries (Li/CFX) is limited due to poor rate capability resulting from the low conductivity of carbon fluoride, which is used as the active material. Therefore, in this study, we applied a carbon coating using pyrolysis fuel oil on carbon fluoride to overcome this limitation and considered its electrochemical performance. An amorphous carbon layer was formed on the surface of the carbon fluoride through carbon coating, and the surface physicochemical properties of the carbon fluoride were meticulously considered based on the heat treatment temperature. The advanced research chemical 1000 heat treated at 450 ℃ (ARC@C450) sample, which was commercial carbon fluoride heat-treated at 450 ℃, showed the largest increase in the concentration of sp2 carbon bonds (62%) and the highest formation of semi-ionic C-F bonds. Also, the primary battery using the ARC@C450 sample as a cathode active material exhibited stable discharge capability at the highest rate of 5 C (392 mAh/g), and the Rct value was reduced by 53% compared to the untreated sample. Therefore, we proposed pyrolysis fuel oil-based carbon coating as a method to overcome the low conductivity of carbon fluoride, and the carbon-coated carbon fluoride showed excellent rate performance, suggesting its potential application in high-power primary batteries.

Simultaneous Absorption of NO and SO2 in Flue gas Using Fe(II)EDTA2- absorbent and Electrochemical Recovery Technology for Gas Reabsorption (Fe(II)EDTA2- 흡수액을 이용한 배가스내 NO, SO2 동시 흡수 및 재흡수를 위한 전기화학적 회수기술 연구)

  • Yoon Hee Kim;Jiyull Kim;Sang Bin Kim;Ji Bong Joo
    • Journal of the Korea Organic Resources Recycling Association
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    • v.32 no.3
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    • pp.43-56
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    • 2024
  • In this study, we investigate wet absorption process and the performance and regeneration of Fe(II)EDTA2- absorbents, electrodeposition of the reducing agent for recovery of metal powder and re-absorption performance using regenerated absorbed for the simultaneous removal of nitrogen oxides (NO) and sulfur oxides (SO2) emitted from flue gas. As a result of a simultaneous absorption experiment of NO and SO2 under the presence of oxygen, the antagonistic effects of SO2 and O2 in the absorption solution resulted in the regeneration of Fe(III)EDTA- and Fe(II)EDTA-NO2- to Fe(II)EDTA2-, inducing the maintained neutral pH and maintained NO2 absorption, thereby greatly improving the simultaneous absorption performance of NO and SO2. In addition, after regenerating the Fe(II)EDTA2- absorbent with Zn metal powder as a reducing agent, electrodeposition was performed to recover the remaining reducing agent. During the electrodeposition process, the high Zn recovery efficiency (approximately 57.50%) was observed at an applied voltage of 4 V, and the total absorption amount of NO was also significantly improved.

Relationship between Clozapine-Induced Therapeutic Responses and Plasma Homovanillic Acid and 5-Hydroxyindoleacetic Acid Levels in Patients with Chronic Schizophrenia (만성 정신분열증 환자에서 Clozapine의 치료반응과 혈장 Homovanillic Acid 및 5-Hydroxyindoleacetic Acid 농도와의 관계)

  • Kim, Chan-Hyung;Lee, Hong Shick;Kim, Kwang Hyeon;Yoo, Kae Joon
    • Korean Journal of Biological Psychiatry
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    • v.4 no.1
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    • pp.84-94
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    • 1997
  • This study was done to examine changes of plasma homovanillic acid(HVA), 5-hydroxyindoleacetic acid(5-HIAA), and HVA/5-HIAA ratio during an 8-week clozapine trial and to investigate the relationship between the plasma monoamine metabolites and treatment responses. Twenty-seven chronic schizophrenic patiens were treated for 8 weeks with clozapine. The psychopathology was assessed at baseline just clozapine trial and then every 2 weeks until the end of 8-week clozapine treatment using the Positive and Negative Syndrome Scale(PANSS) and the Clinical Global Impression scale(CGI). The plasma HVA and 5-HIAA levels were measured also biweekly using high preformance liquid chromatography with electrochemical detection method. Plasma HVA and 5-HIAA levels were significantly decreased during a 8-week clozapine treatment, although plasma HVA/5-HIAA ratio showed no significant change. The changes of plasma HVA levels were in significant correlations with the changes of PANSS positive scores, of general psychophathology scores, and changes of total socres. The changes of plasma 5-HIAA levels were in signfificant correlations with the changes of PANSS negative scores. But the changes of plasma HVA/5-HIAA ratio had no significant correlation with any PANSS subscale score changes. 48% of the patients treated with clozapine was categorized as responders, who showed at least a 20% decrease in PANSS total socre and a CGI severity score of mildly ill or less(${\leq}3$) at the end pint of the study. The baseline plasma HVA levels and HVA/5-HIAA ratio were significantly higher in responders(N=13) than in nonresponders (N=14). But no significant difference in baseline levels of plasma 5-HIAA was found between responders and nonresponders. At the end point of the study, there was significant difference in the change of plasma HVA between responders(40.3% decrement) and nonresponders(3.1% increment). But no signficant differences in the change of plasma 5-HIAA and the change of plasma HVA/5-HIAA ratio between responders and nonresponders were observed. These results suggest that the antipsychotic effect of clozapine on positive symptoms may be associated with dopaminergic blocking activity, and that on negative symptoms may be associated with serotonergic blocking activity. The baseline plasma HVA levels and the change of HVA levels from baseline may be useful predictors of treatment response with clozapine.

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Research of Corrosion Control Technology for the Product Water of SWRO(Seawater Reverse Osmosis) by using liquid lime (액상소석회를 이용한 SWRO 생산수의 부식제어 연구)

  • Kim, Min-Chul;Hwang, Kyu-Won;Woo, Dal-Sik;Yoon, Seok-Min;Kwak, Myung-Hwa
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.1
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    • pp.529-536
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    • 2011
  • In this study, we confirmed that the SWRO(Sea Water Reverse Osmosis) production water has more hard corrosiveness than the tap water by fundamental experiment. According to the result, the target of this study was aimed at developing maintenance and anti-corrosion method. In the early stages of the research, batch tests using mild steel coupons and electrochemical experiments were applied to compare the corrosiveness between SWRO production water and the tap water. After then, two corrosion control methods for SWRO production water were applied. Liquid lime($Ca(OH)_2$) and Carbon Dioxide($CO_2$) were inserted and compared with the combination of liquid lime with phosphate corrosion inhibitor and carbon dioxide. The water qualities were evaluated through LSI(Langelier Saturation Index) and proper injection ratio was deduced by the result. Since then, simulated loop system test were performed to evaluate anti-corrosion effect depending on corrosion inhibitors. Subsequently, carbon steel pipes equipped at the loop system were detached for SEM, EDX and XRD analysis to acquire quantitative and qualitative data of the major corrosion products inside the pipes. In conclusion, the controled groups with anti-corrosion techniques applied were effective by appearing 97.4% and 90.9% of improvements in both case of liquid lime and the liquid lime with a phosphate corrosion Inhibitor. furthermore, major components of scale were iron oxides, on the other hand, protective effect of film formation by calcium carbonate($CaCO_3$) could be confirmed.

Precalcification Treatment of $TiO_2$ Nanotube on Ti-6Al-4V Alloy (Ti-6Al-4V 합금 표면에 생성된 $TiO_2$ 나노튜브의 전석회화 처리)

  • Kim, Si-Jung;Park, Ji-Man;Bae, Tae-Sung;Park, Eun-Jin
    • The Journal of Korean Academy of Prosthodontics
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    • v.47 no.1
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    • pp.39-45
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    • 2009
  • Statement of problem: Recently precalcification treatment has been studied to shorten the period of the implant. Purpose: This study was performed to evaluate the effect of precalcification treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy. Material and methods: Specimens of $20{\times}10{\times}2\;mm$ in dimensions were polished sequentially from #220 to #1000 SiC paper, ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. The nanotubular layer was processed by electrochemical anodic oxidation in electrolytes containing 0.5 M $Na_2SO_4$ and 1.0 wt% NaF. Anodization was carried out using a regulated DC power supply (Kwangduck FA, Korea) at a potential of 20 V and current density of $30\;㎃/cm_2$ for 2 hours. Specimens were heat-treated at $600^{\circ}C$ for 2 hours to crystallize the amorphous $TiO_2$ nanotubes, and precalcified by soaking in $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. To evaluate the bioactivity of the precalcified $TiO_2$ nanotube layer, hydroxyapatite formation was investigated in a Hanks' balanced salts solution with pH 7.4 at $36.5^{\circ}C$ for 2 weeks. Results: Vertically oriented amorphous $TiO_2$ nanotubes of diameters 48.0 - 65.0 ㎚ were fabricated by anodizing treatment at 20 V for 2 hours in an 0.5 M $Na_2SO_4$ and 1.0 NaF solution. $TiO_2$ nanotubes were composed with strong anatase peak with presence of rutile peak after heat treatment at $600^{\circ}C$. The surface reactivity of $TiO_2$ nanotubes in SBF solution was enhanced by precalcification treatment in 0.5 M $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. The immersion in Hank's solution for 2 weeks showed that the intensity of $TiO_2$ rutile peak increased but the surface reactivity decreased by heat treatment at $600^{\circ}C$. Conclusion: This study shows that the precalcified treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy enhances the surface reactivity.

STUDY ON THE RELATIONSHIP BETWEEN ONTOGENY OF SEROTONIN SYSTEM AND PSYCHOPATHOLOGY IN CONDUCT DISORDER (행동장애에 있어서 Serotonin계의 개체발생적인 과정과 정신병리와의 상호관계에 관한 연구)

  • Shin, Sun-Woong;Shin, Min-Sup;Hwang, Jun-Won;Kim, Boong-Nyun;Cho, Soo-Churl
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.14 no.1
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    • pp.112-122
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    • 2003
  • Objectives:Considerable data indicate that diminished serotonergic activity is related to aggressive behavior. In order to understand the biological etiology in conduct disorder, we studied the relationships of plasma serotonin and 5-HIAA levels in conduct disorders to measures of aggression, violation of rules and oppositional defiant behavior. Methods:Subjects were selected from inpatients and outpatients department of the Division of Child and Adolescent Psychiatry of Seoul National University Hospital. 41 conduct disorders(18 childhoodonset type, 23 adolescent-onset type) and 23 normal controls were included in this study. For the assessment of aggression, rule violation and oppositional behavior, parents completed the rating scale for conduct disorder and oppositional behavior based on the DSM-IV diagnostic criteria. Plasma serotonin and 5-HIAA levels were determined by HPLC with electrochemical detection. Results:1) Plasma 5-HT and 5-HIAA levels were not significantly different among childhood-onset conduct disorder, adolescent-onset conduct disorder and normal control subjects. 2) No significant correlations were found between plasma 5-HT levels and aggression or rule violation. 3) Plasma 5-HT levels showed significant positive correlations with oppositional behavior both in childhood-onset conduct disorder and adolescent-onset conduct disorder. 4) Age-related changes were not found in plasma 5-HT and 5-HIAA levles. Conclusion:Our findings do not support the hypothesis that dysregulation of serotonergic function may be associated with aggresson. Instead, our data suggest that serotonergic function is more closely related with oppositional behavior than aggression.

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Alteration of Biosynthesis and Secretion of Adrenal Catecholamines in Cycling Rat (발정주기 중 흰쥐 부신에서의 카테콜아민 합성과 분비 변화)

  • 이성호
    • Development and Reproduction
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    • v.6 no.2
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    • pp.105-110
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    • 2002
  • Numerous hormones are involved in the regulation of reproduction. Among them, estrogen and progesterone are the most important ovarian steroid hormones regulating female fertility. On the other hand, diverse stressors impede female receptivity and fertility. Since norepinephrine(NE) and epinephrine(E) are released from the adrenal during stress, it might play a role in stress-induced disruptions of fEmale reproductive parameters. The present study was performed to analyze the changes in adrenal catecholaminergic activities in cycling rats. The tissue content and secretion level of catecholamines were determined by high performance liquid chromatography coupled with electrochemical detector(HPLC-ECD). Adrenomedullary content of norepinephrine(NE) was increased on proestrus stage (59.47 $\pm$ 6.86 ug/gland), peaked on diestrus I stage(65.22 $\pm$ 5.99 ug/gland), and was nadir on diestrus II stage(41.63 $\pm$ 1.33 ug/gland). The highest E content was observed on proestrus stage(361.86 $\pm$ 15.58 ug/gland) while the lowest level was on diestrus II stage(285.58 $\pm$ 12.25 ug/gland). In addition to these observations, a significant reduction of the NE : E ratio was observed (1 : 4.81 on diestrus I vs 1 : 6.13~7.02 on other stages). In vitro secretion of adrenal NE and E was increased on proestrus stage, peaked on estrus stage, and decreased on diestrus II stage. Interestingly, the NE : E ratio in conditioned media was significantly increased on estrus stage (1 : 3.32 vs 1 : 2.34~2.65 on other stages. The biosynthesis of NE and E is mediated by tyrosine hydroxylase(TH) and phenylethanolamine-N-methyltransferase(PNMT) which acts conversion of tyrosine into DOPA and NE into E, respectively. These finding demonstrated that sex steroids, during setrous cycle, seem to be able to modify the adrenal catecholamines biosynthesis and secretion with stage-specific manner by modulation of the enzyme activities.

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