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Byambasuren, U.,Jeon, Y.,Altansukh, D.,Shul, Y. G. Springer Science + Business Media 2016 Journal of solid state electrochemistry Vol.20 No.3
<P>Doped mesoporous carbons comprising nitrogen, boron, and phosphorus (N, B, and P, respectively) were prepared as non-Pt catalysts for oxygen reduction reaction (ORR) in an acidic solution. The N-doped carbons were varied to increase their catalytic activity through by additionally doping of B and P. All the mesoporous carbons were synthesized by carbonizing polyaniline at 900 degrees C for the N species, while the B and P species were inserted into the carbon structure at the carbon growth step. The linear sweep voltammogram recorded in the acidic solution showed that the ORR activity of the N-doped carbon catalysts increased significantly after the addition of B. An approximately 19 % increase in the pyridinic N content at the carbon surface was observed, along with B-N-C moieties with a binding energy of 399.5 eV. The non-precious metal ORR catalysts were prepared via pyrolysis, with the insertion of an additional transition metal (iron, Fe). The deconvoluted X-ray photoelectron spectroscopy (XPS) results showed that the Fe-N peak was generated after the pyrolysis. The peak intensity of the quaternary N also increased compared with the pyridic and pyrrolic N, which indicates that Fe serves to catalyze the modification of N species. The numerical examinations showed that N- and B-doped mesoporous carbon (NBC) 1.5 % Fe had the highest limited current (4.94 mA/cm(2)), with the B-doped carbon still the most active mesoporous carbon catalyst for ORR. As a result, it can be said that Fe positively contributes to the formation of graphitic N, which is known to be an active site for ORR. The cyclic voltammetry results showed that the peak area of the NBC 1.5 % Fe catalyst was larger than that of the N-doped mesoporous carbon (NC) 1.5 % Fe catalyst. It was concluded that B doping enhances the ORR activity and the stability of carbon materials even after 1000 cycles under acidic conditions.</P>
Byambasuren Gerelt-Od,김재광,신은선,강현철,김나영,조창신,손형빈,윤성훈 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.96 No.-
The inherent risk of side reactions in lithium ion batteries (LIBs) is a crucial issue for large battery packs. To mitigate this problem, there have been previous studies that have attempted to reveal the possiblechemical reactions from decomposition of electrolytes and electrode materials’ reactions during cycling. In particular, the gases expelled during decomposition have garnered research attention as they areexplosive,flammable, toxic, and raise the inner pressure of a cell drastically. In addition, it is important tounderstand thermal effects on gas evolution or degradation of the electrode layer because batteries arenormally exposed to a warm operation condition. Herein, the gases expelled within commercial 18650cylindrical type LIB cells were investigated in moderate thermal conditions in a charged state. Theinvestigation was conducted using a lab-made in situ Raman spectroscopic analysis system andperforming comprehensive transient electrochemical analyses. Our Raman spectroscopy system couldexplore the battery reactions non-disruptively, which is critical for the interior of a cell. Through this insitu technique, the gas expelling trends upon the thermal conditions were elucidated; furthermore,detrimental effects of gas generation reactions to a cell integrity were proposed through comparison withthe electrochemical results.
Ulziidelger Byambasuren,Yukwon Jeon,Dorjgotov Altansukh,Yunseong Ji,Yong-Gun Shul 한국탄소학회 2016 Carbon Letters Vol.17 No.-
Nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a dual transition metal system were synthesized as non-Pt catalysts for the ORR. The highly nitrogen doped OMCs were prepared by the precursor of ionic liquid (3-methyl-1-butylpyridine dicyanamide) for N/C species and a mesoporous silica template for the physical structure. Mostly, N-doped carbons are promoted by a single transition metal to improve catalytic activity for ORR in PEMFCs. In this study, our N-doped mesoporous carbons were promoted by the dual transition metals of iron and cobalt (Fe, Co), which were incorporated into the N-doped carbons lattice by subsequently heat treatments. All the prepared carbons were characterized by via transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). To evaluate the activities of synthesized doped carbons, linear sweep was recorded in an acidic solution to compare the ORR catalytic activities values for the use in the PEMFC system. The dual transition metal promotion improved the ORR activity compared with the single transition metal promotion, due to the increase in the quaternary nitrogen species from the structural change by the dual metals. The effect of different ratio of the dual metals into the N doped carbon were examined to evaluate the activities of the oxygen reduction reaction.
Gerelt-Od, Byambasuren,Kim, Hyosung,Lee, Uk Jae,Kim, Jaekwang,Kim, Nayeong,Han, Yoo Joong,Son, Hyungbin,Yoon, Songhun Electrochemical Society 2018 Journal of the Electrochemical Society Vol.165 No.2
<P>A long-term in-situ measurement method for evolved gases in commercial 18650 cylindrical lithium ion batteries (LIBs) is proposed using Raman spectroscopy. Hydrogen, methane, carbon dioxide, and carbon monoxide were the main gases detected from cells at 4.2-4.8 V for 1800 h. Gas evolution rates were determined by the aging time and the staying potential, resulting in a nonlinear partial-pressure-dependence as a function of the aging time. Initially, the evolution of carbon dioxide and carbon monoxide was significant. After potential-dependent onset times, hydrogen and methane generation increased suddenly. At low potential ranges of 4.2-4.4 V, mostly hydrogen gas was generated, whereas at high potential ranges (>4.6 V), methane becames dominant. Even at 4.4 V, importantly, the absolute accumulative H-2 gas pressure was >3 atm, raising the requirement to monitor such gas for better safety even under nominal operating conditions. Moreover, cumulative partial pressures of the detected gases exceeded the range 5-10 atm, which was associated with the staying potential. An evolution mechanism through which the gas is converted from hydrogen to methane is proposed and discussed. The electrochemical analysis of the aged LIBs showed that the capacity fade was accelerated by the increase in the staying potential while the resistances remained similar. (c) 2018 The Electrochemical Society.</P>
Yong-Gun Shul,Ulziidelger Byambasuren,Yu Kwon Jeon,Dorjgotov Altansukh,Yunseong Ji 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.6
The particle size effect of N-doped mesoporous carbon was investigated for ORR activity in acid condition and for issue of a mass transfer and gas diffusion in PEMFCs. As for a non-Pt ORR catalyst, nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a various particle sizes with the range of the average 20, 45 and 75 μm were synthesized by the precursor of polyaniline for the N/C species, and a mesoporous silica template was used for the physical structure for preparation of nitrogen doped OMCs. The N-doped mesoporous carbons are promoted by a transition metal (Fe) to improve catalytic activity for ORR in PEMFCs. All the prepared carbons were characterized by via scanning electron microscopy (SEM), and to evaluate the activities of synthesized doped carbons, linear sweep was recorded in an acidic solution to compare the ORR catalytic activities values for the use in the PEMFC system. The surface area and pore volume were increased as the particles decreased, which was effective for the mass transfer of the reactant for higher activity at the limiting current regions.
Design of Au core-Palladium alloy shell nanoparticle for oxygen reduction reaction in fuel cells
이예연,설용건,김형수,전유권,박명근,( Ulziidelger Byambasuren ),황주순 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Platinum based nanomaterials are usually used as the electrocatalysts for both the cathode(oxygen reduction) and anode(hydrogen oxidation) reactions. However, the high cost of Pt in cathode catalyst and the slow kinetics of oxygen reduction reaction (ORR) on Pt-based catalysts hinder the commercialization of fuel cells. Instead of using platinum, recent studies have focused on the discovery of non platinum electrocatalysts which have excellent electrocatalytic activity and chemical stability. In this study, we synthesized gold core/palladium-Cobalt alloy shell catalysts. The developed catalysts showed excellent catalytic activity than Au core/Pd shell catalysts. The structural information and electrocatalytic activities of the Au core/Pd-Ir alloy shell nanoparticles were analyzed by XRD, XPS, HR-TEM, ORR test and cyclic voltammetry(CV).