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Lee, Ilbok,Jeong, Gyoung Hwa,An, Soyeon,Kim, Sang- Wook,Yoon, Songhun Elsevier BV * North-Holland 2018 Applied Surface Science Vol.429 No.-
<P><B>Abstract</B></P> <P>Herein, MnNi-layered double hydroxides (LDH) were imbibed within the interlayers of graphene nanosheets. The anionic surfactant, sodium dodecyl sulfate played a role of graphite exfoliator adding interaction with metal cations. Using this process, layered MnNi-LDH-graphene nanocomposite was prepared without formation of graphene oxide. When applied into pseudocapacitor electrode, LDH-graphene with optimal ratio between Mn and Ni exhibited very stable cycle with 90% at 1400 cycles and high energy 47.29Whkg<SUP>−1</SUP> at the power density of 7473Wkg<SUP>−1</SUP>, which was attributed to highly stable layered LDH structure within conductive graphene layers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 3D MnNi-layered double hydroxides (LDH)/graphene were synthesized from graphite. </LI> </UL> </P> <P> <ce:list id='lis0010'> <ce:list-item id='lsti0010'> <ce:label>•</ce:label> <ce:para id='par0010' view='all'>Nanocomposite-on-graphene electrode provides fast and efficient diffusion of electrolyte ions to active material surface.</ce:para> </ce:list-item> <ce:list-item id='lsti0015'> <ce:label>•</ce:label> <ce:para id='par0015' view='all'>Mn1Ni3-LDH-G composite electrode shows optimum electrochemical performance.</ce:para> </ce:list-item> </ce:list> </P>
Lee, Ilbok,Kim, Jaekwang,Kim, Daeun,Kim, Hyosung,Hwang, Kee Bum,Son, Hyungbin,Yoon, Songhun Pergamon Press 2017 Electrochimica Acta Vol. No.
<P><B>Abstract</B></P> <P>The concentration of sulfate ions was continuously monitored by Raman spectroscopy during the preparation of cathode material precursors. The obtained spectra were used for the quantitative analysis of sulfate ions by comparison with a reference solution, and a gradual increase of sulfate ion concentration was detected. Using a mathematical approach, a time-dependent equation describing sulfate ion concentration was theoretically derived, and the calculated concentrations were compared with the measured ones, showing good agreement between these values. Due to the increased sulfate ion concentration, the metal hydroxide cathode precursor became more contaminated with elemental sulfur. Two as-obtained hydroxide powders with different sulfur impurity contents were calcined with a lithium source, producing cathode materials. Electrochemical analysis of the prepared cathode materials showed that morphological aspects (such as particle size) more highly affected the cathode performance more than the sulfur impurity content.</P>
Jeong, Gyoung Hwa,Lee, Ilbok,Lee, Donghyun,Lee, Hea-Min,Baek, Seungmin,Kwon, O-Pil,Kumta, Prashant N,Yoon, Songhun,Kim, Sang-Wook IOP 2018 Nanotechnology Vol.29 No.19
<P>The fabrication of <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods embedded in graphene sheets and their application as electrochemical charge storage electrodes is reported. From the surfactant treatment of raw graphite, graphene was directly prepared and its nanocomposite with <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods distributed between graphene layers (<I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G) was synthesized by a hydrothermal method. When applied as an anode in lithium-ion batteries, the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G anode exhibits greatly improved charge and discharge capacities of 790 and 627 mAhаиаg<SUP>−1</SUP>, respectively, with unexpectedly high initial efficiency of 82%. The observed discharge capacity reflected that at least 3.7 mol of Li<SUP>+</SUP> is selectively accumulated within the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase (Li<SUB>x</SUB>CoV<SUB>3</SUB>O<SUB>8</SUB>, xа>а3.7), indicative of significantly improved Li<SUP>+</SUP> uptake when compared with aggregated <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods. Moreover, very distinct peak plateaus and greatly advanced cycling performance are observed, showing more improved Li<SUP>+</SUP> storage within the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase. As a supercapacitor electrode, moreover, our composite electrode exhibits very high peak pseudocapacitances of 2.71 Fаиаcm<SUP>−2</SUP> and 433.65 Fаиаg<SUP>−1</SUP> in the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase with extremely stable cycling performance. This remarkably enhanced performance in the individual electrochemical charge storage electrodes is attributed to the novel phase formation of <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> and its optimized nanocomposite structure with graphene, which yield fast electrical conduction through graphene, easy accessibility of ions through the open multilayer nanosheet structure, and a relaxation space between the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G.</P>
Zhou, Yuanyuan,Lee, Ilbok,Kim, Daeun,Han, Seunghee,Kim, Jae-Kwang,Lee, Donghyun,Ko, Song Won,Pyo, Sung Gyu,Son, Hyungbin,Yoon, Songhun American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.1
<P>Using a stabilizing agent-assisted co-assembly method, a novel nanocomposite of mesoporous carbon embedded with uniform tungsten oxide nanorods is obtained, which is converted into carbon-sheathed tungsten oxide nanoparticles by delicate calcination and further reduction. Through optimization of tungsten content, it is found that highly crystalline tungsten oxide nanoparticles are uniformly coated with an ultra-thin carbon layer. When applied into electrochemical charge-storage electrodes for supercapacitor and lithium-ion battery, an excellent average capacitance (129 F g(-1), above 400 F cm(-3)), higher rate performance and significantly advanced cycle stability are observed. These improved charge storage properties are attributed to improved electrical conductivity and enhanced structural stability, which is induced by uniform carbon coating on partially reduced tungsten oxide nanoparticles.</P>
Novel estimation method of operating life in lithium-ion pouch cells
Kim, Hyosung,Kim, Jaekwang,Kim, Nayeong,Lee, Ilbok,Hwang, Keebum,Bae, Joongho,Yoon, Songhun THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.67 No.-
<P><B>Abstract</B></P> <P>Herein, a novel operating life (OL) test method was evaluated with 200mAh pouch-type lithium-ion batteries. By combining the calendar life (CL) test with intermediate pulse power cycling, more realistic life prediction was possible, which encompassed real operation of batteries accompanying with thermal acceleration. Larger capacity decrease and resistance increase of pouch cell were observed in the OL test, which was well explained using the SEI film growth model. After dissemble of pouch cell, capacity loss and resistance increase mostly occurred within anode, reflecting that SEI film growth on anode surface was highly attributable to cell degradation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Suggestion of novel operating life prediction. </LI> <LI> Intermediate pulse power cycling to simulate vehicle operation. </LI> <LI> Combination of pulse power cycling and thermal degradation by calendar life prediction. </LI> <LI> Surface film growth model to explain capacity and resistance change. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Anti-inflammatory Effect of Arbitrary Waveform Generator Treatment in Rats
Myung-Gyou Kim,Se-Na Lee,Ilbok Seo,Kanghyun Leem,Kee Sun Ham,Hye Kyung Kim 대한의생명과학회 2008 Biomedical Science Letters Vol.14 No.1
Inflammation is the complex biological response of injured tissues to harmful stimuli. A cascade of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells within the injured tissue. The immune system is often involved with inflammatory disorders, demonstrated in both allergic reactions and some myopathies, with many immune system disorders resulting in abnormal inflammation. An Arbitrary Waveform Generator (AWG) is a piece of electronic test equipment used to generate electrical waveforms for the treatment of patients. The patients with gastritis and arthritis have been known to have a relatively favorable prognosis with AWG treatment. Accordingly, we examined the effects of AWG treatment in gastritis and arthritis animal model. The compound 48/80 was used to induce animal gastritis model. The tissue malone dialdehyde (MDA) and serum histamine levels, and the activity of superoxide dismutase (SOD) in stomach tissue were measured. The tissue MDA and serum histamine levels in AWG treated groups exhibited the decreased tendency compared with control group, whereas the tissue SOD activity was slightly increased. The Freund's complete adjuvant was used to induce animal arthritis model as well. The paw edema volume and the width of ankle joint were determined. The AWG treatment significantly decreased the paw edema volume after 5th day of treatment. Although further studies should be performed to confirm the effects of AWG treatment, present study suggest that AWG treatment might be used as a complementary treatment for the gastritis or arthritis treatment.
Clarification of performance degradation of 20 Ah LIB pouch cell after use in electric bus
Cho, Yong-Nam,Hwang, Keebum,Bae, Joong Ho,Kim, Jaekwang,Lee, Ilbok,Kim, Nayoung,Ahn, Junghoon,Song, Jun-Ho,Yoon, Songhun Elsevier 2018 Journal of Electroanalytical Chemistry Vol.829 No.-
<P><B>Abstract</B></P> <P>Herein, performance degradation of pouch type of 20 A h lithium ion battery from electric bus is clarified after a classification using the resistance value from A to D grade. The obtained cells are carefully disassembled to produce cathode, anode, and separator. Scanning electron microscopy and energy dispersive spectroscopy analysis reveal that morphological change of electrode mostly occur in the anodes surface in D-grade cells, while cathodes of all the grades mostly remain similar. Although the change of crystalline structure of all electrodes is negligible, a growth of solid-electrolyte interphase film mostly happen in the D-grade anodes, which is confirmed by X-ray photoelectron spectroscopy analysis. Furthermore, the degradation of cycle and rate performance happen in the anode of D-grade cells, whereas the cathodes remain invariant irrespective of grade. Furthermore, the disassembled separators exhibit that the Gurley number of separators is commonly increased in the used cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The used 20 Ah lithium ion pouch cells from electric bus were classified using resistance. </LI> <LI> The LIB cells separated in 4 grade level were dissembled to obtain cathode, anode and separator. </LI> <LI> Surface film increase occurred in anode in D graded LIB cells. </LI> <LI> Resistance increase and capacity decrease were mostly attributed to anode degradation. </LI> <LI> Cathode and separator remained less-changed by real operation. </LI> </UL> </P>