활성화된(Fe_1-xMn_x)₃O_4-_δ과 (Fe_1-xCo_x)₃O_4-_δ의 이산화탄소 분해 특성

박원식,오경환,이상인,서동수,Park, Won-Shik,Oh, Kyoung-Hwan,Rhee, Sang-In,Suhr, Dong-Soo 한국재료학회 2013 한국재료학회지 Vol.23 No.4

Activated magnetite ($Fe_3O_{4-{\delta}}$) has the capability of decomposing $CO_2$ proportional to the ${\delta}$-value at comparatively low temperature of $300^{\circ}C$. To enhance the $CO_2$ decomposition capability of $Fe_3O_{4-{\delta}}$, $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$ and $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$ were synthesized and then reacted with $CO_2$. $Fe_{1-x}Co_xC_2O_4{\cdot}2H_2O$ powders having Fe to Co mixing ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 were synthesized by co-precipitation of $FeSO_4{\cdot}7H_2O$ and $CoSO_4{\cdot}7H_2O$ solutions with a $(NH_4)_2C_2O_4{\cdot}H_2O$ solution. The same method was used to synthesize $Fe_{1-x}Mn_xC_2O_4{\cdot}2H_2O$ powders having Fe to Mn mixing ratios of 9:1, 8:2, 7:3, 6:4, 5:5 with a $MnSO_4{\cdot}4H_2O$ solution. The thermal decomposition of synthesized $Fe_{1-x}Co_xC_2O_4{\cdot}2H_2O$ and $Fe_{1-x}Mn_xC_2O_4{\cdot}2H_2O$ was analyzed in an Ar atmosphere with TG/DTA. The synthesized powders were heat-treated for 3 hours in an Ar atmosphere at $450^{\circ}C$ to produce activated powders of $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$ and $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$. The activated powders were reacted with a mixed gas (Ar : 85 %, $CO_2$ : 15 %) at $300^{\circ}C$ for 12 hours. The exhaust gas was analyzed for $CO_2$ with a $CO_2$ gas analyzer. The decomposition of $CO_2$ was estimated by measuring $CO_2$ content in the exhaust gas after the reaction with $CO_2$. For $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$, the amount of $Mn^{2+}$ oxidized to $Mn^{3+}$ increased as x increased. The ${\delta}$ value and $CO_2$ decomposition efficiency decreased as x increased. When the ${\delta}$ value was below 0.641, $CO_2$ was not decomposed. For $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$, the ${\delta}$ value and $CO_2$ decomposition efficiency increased as x increased. At a ${\delta}$ value of 0.857, an active state was maintained even after 12 hours of reaction and the amount of decomposed $CO_2$ was $52.844cm^3$ per 1 g of $(Fe_{0.5}Co_{0.5})_3O_{4-{\delta}}$.

Li2CO3 첨가에 따른 입방정 Bi1.5Zn1.0Nb1.5O7(c-BZN)의 상 변화 및 그에 따른 유전특성 변화 연구

이유선,김윤석,최슬원,한성민,이경호 한국마이크로전자및패키징학회 2023 마이크로전자 및 패키징학회지 Vol.30 No.4

(1-4x)Bi1.5Zn1.0Nb1.5O7-3xBi2Zn2/3Nb4/3O7-2xLiZnNbO4(x=0.03-0.21) 조성의 새로운 저온 동시 소성 세라믹(LTCC) 유전체는 Bi1.5Zn1.0Nb1.5O7-xLi2CO3(x=0.03-0.21) 혼합물을 850oC~920oC에서 4 시간 반응성 액상소결(reactive liquid phase sintering)을 하여 제조하였다. 소결이 진행되는 동안 Li2CO3는 Bi1.5Zn1.0Nb1.5O7과 반응하여 Bi2Zn2/3Nb4/3O7 과 LiZnNbO4를 생성하였고 얻어진 소결체의 상대 소결밀도는 이론 밀도의 96% 이상이었다. 초기 Li2CO3 함량(x)을 조절하여 최종 소결체내에 존재하는 Bi1.5Zn1.0Nb1.5O7, Bi2Zn2/3Nb4/3O7 및 LiZnNbO4 상의 상대적인 함량을 제어함으로써높은 유전율(r), 낮은 유전손실(tan ) 및 NP0 특성(TC ≤ ±30 ppm/oC)의 유전율 온도계수(TC)를 갖는 유전체를 개발할 수 있었다. Li2CO3의 첨가가 x=0.03 mol에서 x=0.15 mol로 증가함에 따라 얻어진 복합체 내의 Bi2Zn2/3Nb4/3O7와LiZnNbO4의 부피 분율은 증가하였고, Bi1.5Zn1.0Nb1.5O7의 부피 분율은 감소하였다. 그 결과 복합체의 유전율(r)은 148.38 에서 126.99로 유전손실(tan )은 5.29×10-4에서 3.31×10-4로 그리고 유전율 온도계수(TC)는 -340.35 ppm/oC에서 299.67 ppm/oC로 변화되었다. NP0 특성을 갖는 유전체는 Li2CO3의 함량이 x=0.09일 때 얻을 수 있었고, 이 때의 유전율(εr)은143.06, 유전손실(tan )값은 4.31×10-4, 그리고 유전율 온도계수(TC)값은 -9.98 ppm/oC 이었다. Ag전극과의 화학적 호환성 실험은 개발된 복합 재료는 Ag 전극과 동시 소성 과정에서 전극과 반응이 없음을 보여주었다. A novel low-temperature co-fired ceramic (LTCC) dielectric, composed of (1-4x)Bi1.5Zn1.0Nb1.5O7-3xBi2Zn2/3Nb4/3O7- 2xLiZnNbO4 (x=0.03-0.21), was synthesized through reactive liquid phase sintering of Bi1.5Zn1.0Nb1.5O7-xLi2CO3 ceramic at temperatures ranging from 850°C to 920°C for 4 hours. During sintering, Li2CO3 reacted with Bi1.5Zn1.0Nb1.5O7, resulting in the formation of Bi2Zn2/3Nb4/3O7, and LiZnNbO4. The resulting sintered body exhibited a relative sintering density exceeding 96% of the theoretical density. By altering the initial Li2CO3 content (x) and consequently modulating the volume fraction of Bi1.5Zn1.0Nb1.5O7, Bi2Zn2/3Nb4/3O7, and LiZnNbO4 in the final sintered body, a sample with high dielectric constant (εr), low dielectric loss (tan δ), and the temperature coefficient of dielectric constant (TCε) characterized by NP0 specification (TCε ≤ ±30 ppm/°C) was achieved. As the Li2CO3 content increased from x=0.03 mol to x=0.15 mol, the volume fraction of Bi2Zn2/3Nb4/3O7 and LiZnNbO4 in the composite increased, while the volume fraction of Bi1.5Zn1.0Nb1.5O7 decreased. Consequently, the dielectric constant (εr) of the composite materials varied from 148.38 to 126.99, the dielectric loss (tan δ) shifted from 5.29×10-4 to 3.31×10-4, and the temperature coefficient of dielectric constant (TCε) transitioned from -340.35 ppm/°C to 299.67 ppm/°C. A dielectric exhibiting NP0 characteristics was achieved at x=0.09 for Li2CO3, with a dielectric constant (εr) of 143.06, a dielectric loss (tan δ) value of 4.31x10-4, and a temperature coefficient of dielectric constant (TCε) value of -9.98 ppm/°C. Chemical compatibility experiment with Ag electrode revealed that the developed composite material exhibited no reactivity with the Ag electrode during the co-firing process.

리튬이차전지 양극활물질용 LiMn2O4-LiNi1/3Mn1/3Co1/3O2의 전기화학적 특성

구할본,공명철,Van Hiep Nguyen 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.5

In this work, LiMn2O4 and LiNi1/3Mn1/3Co1/3O2 cathode materials are mixed by some specific ratios to enhance the practical capacity, energy density and cycle performance of battery. At present, the most used cathode material in lithium ion batteries for EVs is spinel structure-type LiMn2O4. LiMn2O4 has advantages of high average voltage, excellent safety, environmental friendliness, and low cost. However, due to the low rechargeable capacity (120 mAh/g), it can not meet the requirement of high energy density for the EVs, resulting in limiting its development. The battery of LiMn2O4-LiNi1/3Mn1/3Co1/3O2 (50:50 wt%) mixed cathode delivers a energy density of 483.5 mWh/g at a current rate of 1.0 C. The accumulated capacity from 1st to 150th cycles was 18.1 Ah/g when the battery is cycled at a current rate of 1.0 C in voltage range of 3.2~4.3 V. 본 연구에서는 양극활물질 LiMn2O4의 에너지 밀도를 높이고자 일정한 비율별로 가역용량이 높은 양극활물질 LiNi1/3Mn1/3Co1/3O2을 단순 추가 혼합하는 방식으로 양극활물질 LiMn2O4-LiNi1/3Mn1/3Co1/3O2를 제조하여 전기화학적 특성을 평가 분석하였다. 양극활물질 LiNi1/3Mn1/3Co1/3O2를 50 wt% 혼합하였을 때 혼합비율 대비 용량증가폭이 가장 높았고, 평균전압 감소폭이 가장 낮았기에 에너지밀도는 483.5 mWh/g으로 높았다. 또한, 150회 충·방전이 진행되는 동안 가역용량이 높은 양극활물질 LiNi1/3Mn1/3Co1/3O2의 혼합으로 하여 누적 방전용량은 양극활물질 LiMn2O4로 제작한 코인셀에 비하여 모두 증가하였으며, 양극활물질 LiNi1/3Mn1/3Co1/3O2를 50 wt% 혼합하여 제작한 코인셀이 18.1 Ah/g으로 가장 높게 나타내었다.

하이브리드 커패시터의 열안정성 개선을 위한 LiFePO₄ 복합양극 소재에 관한 연구

권태순 ( Tae-soon Kwon ),박지현 ( Ji-hyun Park ),강석원 ( Seok-won Kang ),정락교 ( Rag-gyo Jeong ),한상진 ( Sang-jin Han ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.2

고온에서 Mn 이온 용출에 의한 성능저하를 보이는 스피넬 결정구조의 LiMn₂O₄ 양극 하이브리드 커패시터의 대안으로 열안정성이 높은 올리빈 결정구조의 LiFePO₄ 기반 복합양극 소재의 적용가능성을 연구하였다. LiFePO₄/활성탄 셀을 이용한 1.0~2.3 V의 충·방전을 통한 수명평가에서 상온(25 ℃) 및 고온(60 ℃) 조건 모두에서 충·방전 사이클이 진행됨에 따라 음극(활성탄)의 저전압화에 따른 열화로 인한 용량저하 현상이 나타났다. 이의 해결을 위해 50:50 중량비율로 LiFePO₄/LiMn₂O₄, LiFePO₄/Activated carbon 및 LiFePO₄/LiNi_1/3Co_1/3Mn_1/3O₂ 복합양극을 제조하여 모노셀 충·방전 실험을 수행한 결과, 층상구조의 LiNi_1/3Co_1/3Mn_1/3O₂를 사용한 전극이 안정적인 전압거동을 보였다. 또한, 2.3 V 및 80 ℃에서 1,000시간 부하를 통한 고온 안정성 실험에서도 LiFePO₄/LiNi_1/3Co_1/3Mn_1/3O₂ 복합양극이 상용 LiMn₂O₄ 양극에 비해 약 2배 가량 높은 방전용량 유지율을 보였다 The application of composite cathode materials including LiFePO₄ (lithium iron phosphate) of olivine crystal structure, which has high thermal stability, were investigated as alternatives for hybrid battery-capacitors with a LiMn₂O₄ (spinel crystal structure) cathode, which exhibits decreased performance at high temperatures due to Mn-dissolution. However, these composite cathode materials have been shown to have a reduction in capacity by conducting life cycle experiments in which a LiFePO₄/activated carbon cell was charged and discharged between 1.0 V and 2.3 V at two temperatures, 25 ℃ and 60 ℃, which caused a degradation of the anode due to the lowered voltage in the anode. To avoid the degradation of the anode, composite cathodes of LiFePO₄/LiMn₂O₄ (50:50 wt%), LiFePO₄/activated carbon (50:50 wt%) and LiFePO₄/LiNi_1/3Co_1/3Mn_1/3O₂ (50:50 wt%) were prepared and the life cycle experiments were conducted on these cells. The composite cathode including LiNi_1/3Co_1/3Mn_1/3O₂ of layered crystal structure showed stable voltage behavior. The discharge capacity retention ratio of LiFePO₄/LiNi_1/3Co_1/3Mn_1/3O₂ was about twice as high as that of a LiFePO₄/LiMn₂O₄ cell at thermal stability experiment for a duration of 1,000 hours charged at 2.3 V and a temperature of 80 ℃.

P123-Templated Co₃O₄/Al₂O₃ Mesoporous Mixed Oxides for Epoxidation of Styrene

Jung, Mie-Won,Kim, Young-Sil Materials Research Society of Korea 2012 한국재료학회지 Vol.22 No.6

$Co_3O_4$, $Al_2O_3$ and $Co_3O_4$/$Al_2O_3$ mesoporous powders were prepared by a sol-gel method with starting matierals of aluminum isopropoxide and cobalt (II) nitrate. A P123 template is employed as an active organic additive for improving the specific surface area of the mixed oxide by forming surfactant micelles. A transition metal cobalt oxide supported on alumina with and without P123 was tested to find the most active and selective conditions as a heterogeneous catalyst in the reaction of styrene epoxidation. A bBlock copolymer-P123 template was added to the staring materials to control physical and chemical properties. The properties of $Co_3O_4$/$Al_2O_3$ powder with and without P123 were characterized using an X-ray diffractometer (XRD), a Field-Emission Scanning Electron Microscope (FE-SEM), a Bruner-Emmertt-Teller (BET) surface analyzer, and $^{27}Al$ MAS NMR spectroscopy. Powders with and without P123 were compared in catalytic tests. The catalytic activity and selectivity were monitored by GC/MS, $^1H$, and $^{13}C$-NMR spectroscopy. The performance for the reaction of epoxidation of styrene was observed to be in the following order: [$Co_3O_4$/$Al_2O_3$ with P123-1173 K > $Co_3O_4$/$Al_2O_3$ with P123-973 K > $Co_3O_4$-973 K>$Co_3O_4$/$Al_2O_3$-973 K > $Co_3O_4$/$Al_2O_3$ with P123-1473 K > $Al_2O_3$-973 K]. The existence of ${\gamma}$-alumina and the nature of the surface morphology are related to catalytic activity.

리튬 이차전지용 LiMn1.92Co0.08O4, LiNi1-yCoyO2 의 합성과 그들의 혼합물 의 전기화학적 특성

권익현,송명엽,김훈욱 한국수소및신에너지학회 2004 한국수소 및 신에너지학회논문집 Vol.15 No.1

LiMn1.92Co0.08O4와 LiNi1-yCoyO2를 단순화한 연소법에 의하여 합성하고, 그것들의 전기화학적 특성을 조사하였다. 또한 30분동안 밀링하여 준비한 LiMn1.92Co0.08O4 - x wt.%LiNi0.7Co0.3O2 (x=9, 23, 33, 41 and 47) 혼합물 전극의 전기화학적 특성을 조사하였다. x=33 조성의 전극이 가장 큰 초기방전용량(132.0mAh/g at 0.1C)을 나타내었다. x=9조성의 전극은 비교적 큰 초기방전용량(109.9mAh/g at 0.1C)과 우수한 싸이클 특성을 나타내었다. 싸이클링에 따른 혼합물 전극의 방전용량의 감소는 주로 LiNi0.7Co0.3O2의 퇴화에 기인한다고 생각된다. 그런데 LiNi0.7Co0.3O2의 퇴화는 LiMn1.92Co0.08O4로부터 용해된 Mn이 LiNi0.7Co0.3O2를 둘러쌈(coating)으로써 야기되는 것으로 생각된다.

리튬이차전지 양극활물질용 LiMn₂O₄-LiNi_1/3Mn_1/3Co_1/3O₂의 전기화학적 특성

공명철,구할본,Kong, Ming Zhe,Nguyen, Van Hiep,Gu, Hal-Bon 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.5

In this work, $LiMn_2O_4$ and $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ cathode materials are mixed by some specific ratios to enhance the practical capacity, energy density and cycle performance of battery. At present, the most used cathode material in lithium ion batteries for EVs is spinel structure-type $LiMn_2O_4$. $LiMn_2O_4$ has advantages of high average voltage, excellent safety, environmental friendliness, and low cost. However, due to the low rechargeable capacity (120 mAh/g), it can not meet the requirement of high energy density for the EVs, resulting in limiting its development. The battery of $LiMn_2O_4-LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ (50:50 wt%) mixed cathode delivers a energy density of 483.5 mWh/g at a current rate of 1.0 C. The accumulated capacity from $1^{st}$ to 150th cycles was 18.1 Ah/g when the battery is cycled at a current rate of 1.0 C in voltage range of 3.2~4.3 V.

Enhanced electrochemical performance of Li3PO4 coated LiNi0.8Co0.1Mn0.1O2 cathode materials for high-energy Li-ion batteries

Do-Young Hwang,Seung-Hwan Lee 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4

In this paper, we successfully synthesized the Li3PO4 coated Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode and investigatedelectrochemical performances and structure morphology for high-energy lithium-ion battery. The Li3PO4 coated Ni-richLiNi0.8Co0.1Mn0.1O2 shows superior cation mixing and there is no significant change in morphology compared to the pristineNCM. In particular, the Li3PO4 coated Ni-rich LiNi0.8Co0.1Mn0.1O2 exhibits an improved rate capability of 176.5 mAh g^-1 at4.0 C and cyclability of 80.2% (after 80 cycles). Therefore, the Li3PO4 coated Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode can bedeemed as an effective method for next-generation Li-ion batteries.

Activation of formyl CH and hydroxyl OH bonds in HMF by the CuO(1 1 1) and Co₃O₄(1 1 0) surfaces: A DFT study

Ren, Jun,Song, Kai-he,Li, Zhenhuan,Wang, Qiang,Li, Jun,Wang, Yingxiong,Li, Debao,Kim, Chan Kyung Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.456 No.-

<P><B>Abstract</B></P> <P>The first principle calculations with on-site Coulomb repulsion U terms were carried out to investigate the 5-hydroxymethylfurfural (HMF) adsorption on the CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces, two widely used oxidation catalysts. The adsorption of HMF molecule is energetically favoured in both cases, and HMF is more inclined to bridge adsorption via hydroxyl and formyl groups binding with surface O and metal sites. Moreover, the adsorption energy relies on both the coordination type of surface lattice oxygen to which the H atom binds and the formation of H-bond involving hydroxyl and formyl groups on the adsorbed HMF. Also, the hydroxyl OH bond breaking is very easy and is likely to be the first step in HMF oxidation, and then the OH insertion reaction to produce 2,5-furandicarboxylic acid (FDCA). The corresponding experimental results also show that the CuO and Co<SUB>3</SUB>O<SUB>4</SUB> surfaces are promising candidate catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces catalyze the oxidation of 5-hydroxymethylfurfural (HMF). </LI> <LI> Initial binding was formed through bridged-adsorption with O atoms in HMF. </LI> <LI> Oxidation reaction proceeds through the OH bond breaking pathway. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic potential energy diagram for the formyl CH and hydroxyl OH bonds of HMF dissociation on CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces. Obviously, the hydroxyl OH bond breaking is easier than that of the formyl CH bond on the two surfaces, which indicates the first step of oxidation of HMF to FDCA should be hydroxyl OH bond breaking.</P> <P>[DISPLAY OMISSION]</P>

Highly Selective Lithium Recovery from Brine using LNCM/Ag and LNMO/Ag Battery System

( Khino J. Parohinog ),( Chosel P. Lawagon ),( Grace M. Nisola ),( Wook-jin Chung ),( Seong Poong Lee ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-

Lithium shortage is inevitable due its massive demand growth for use in electric vehicles (EVs) and various technologies. Therefore, recovery of lithium from other sources such as seawater, brine, and Li-containing wastewater has been gaining attention in energy-related fields. However, the challenge is to find an environmentally benign and energy-efficient processes with fast Li⁺ production rate for sustainable Li⁺ supply. Electrochemical Li⁺ recovery from aqueous solutions is an attractive method as it provides fast recovery rate. However, several studies on this process are challenged with the stability of the materials in aqueous environment and large amount of energy needed entailing high production cost. Until recently, electrochemical related Li⁺ extraction has yet to realize its feasibility for industrial-scale application. The success of electrochemical method relies on utilizing highly effective electrodes that can selectively capture Li⁺ at a fast rate and at a competitive uptake capacity with minimal energy requirement. Delithiated Li_1-xNi_1/3Co_1/3Mn_1/3O₂ (NCM) or Li_1-xNi_0.5Mn_0.5O₄ (NMO) paired with silver (Ag) were introduced as new electrochemical systems for Li⁺ recovery from brine. Material and electrochemical characterizations confirm Li⁺ selectivity and stability of NMO/Ag or NCM/Ag in aqueous phase. Using brine as Li⁺ feed source, NMO/Ag or NCM/Ag electrochemically captured Li⁺ and Cl- at an applied current (C-rate) and operation time (min step-1). Reversal of the current in a receiving solution prompted the release of LiCl. Under optimal conditions, NCM can produce 96.4% pure Li⁺ from brine by expending 2.60 W·h mol^-1 Li⁺ while NMO can produce 98.1% pure Li+and expending 1.30 - 1.50 W·h mol^-1 Li⁺. In cycled experiments (n = 20), NMO/Ag and NCM/Ag can selectively accumulate Li⁺ from brine demonstrating its stability. These promising results indicate that both electrochemical systems can be developed for highthroughput Li⁺ mining process with low energy requirement. This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2018R1D1A1B07048007).