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Zhao, Xiaohui,Kim, Dul-Sun,Ahn, Hyo-Jun,Kim, Ki-Won,Jin, Chang-Soo,Ahn, Jou-Hyeon The Korean Electrochemical Society 2010 한국전기화학회지 Vol.13 No.3
Sulfur cathodes were prepared by ball milling method with different types of electronic conductors and binders in different ball milling time. The sulfur cell with a cathode prepared in 45 min ball milling time gave an initial discharge capacity of 794mAh/g with Super-P as an electronic conductor and poly(vinylidene fluoride) as a binder. The cathode with multi-walled carbon nanotube as an electronic conductor showed an initial discharge capacity of 944 mAh/g and a discharge capacity of 300 mAh/g after 20 cycles. Cathodes with poly(ethylene oxide) and poly(vinylidene fluoride) as binders showed different cycle performance.
Polyaniline-Coated Mesoporous Carbon/Sulfur Composites for Advanced Lithium Sulfur Batteries
Zhao, Xiaohui,Ahn, Hyo-Jun,Kim, Ki-Won,Cho, Kwon-Koo,Ahn, Jou-Hyeon American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.15
<P>Lithium sulfur (Li–S) batteries have been considered as a promising candidate for high energy density applications with a high theoretical capacity of 1675 mAh g<SUP>–1</SUP> and a high energy density of 2600 Wh kg<SUP>–1</SUP>. In this work, a polyaniline (PANi)-coated mesoporous carbon composite is synthesized by direct polymerization of aniline monomer in mesoporous Ketjenblack (KB) carbon and is used as cathode material for Li–S batteries. Different mass percentages of PANi can be infiltrated into the pores of KB carbon by simply varying the amount of monomer. Sulfur is encapsulated into the composite by the melt diffusion method, and the electrochemical performance of lithium sulfur batteries is investigated. The results indicate that the mass percentage of PANi plays a crucial role in the cycle stability of lithium sulfur batteries. The infiltrated PANi is capable of enhancing the intimate contact of sulfur with carbon and trapping polysulfides, which improves the utilization of active material. However, excess PANi diminishes the pore volume of mesoporous KB carbon, which limits sulfur loading and impairs the capability of cells. The cell with the composite containing 30% of PANi shows an improved cyclability of 675 mAh g<SUP>–1</SUP> after 200 cycles at 0.1 C-rate, demonstrating promising applications in Li–S batteries with high energy density.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-15/jp511846z/production/images/medium/jp-2014-11846z_0010.gif'></P>
Zhao, Xiaohui,Kim, Dul-Sun,Raghavan, Prasanth,Ahn, Jou-Hyeon,Ahn, Hyo-Jun,Ryu, Ho-Suk,Cho, Gyu-Bong,Noh, Jung-Pil Royal Swedish Academy of Sciences 2010 Physica scripta Vol.2010 No.t139
<P>Porous polymer membranes based on poly(vinylidene fluoride-<I>co</I>-hexafluoropropylene) were prepared by the phase inversion process, and the effect of processing parameters, such as the type of solvent and concentration of the polymer solution, on the membrane morphology and electrochemical properties of a polymer electrolyte (PE) was investigated. The membranes prepared were characterized by scanning electron microscopy and differential scanning calorimetry. PEs were prepared by soaking the porous membrane in 1 M LiPF<SUB>6</SUB> in ethylene carbonate/dimethyl carbonate, and their electrochemical performance was studied. The polymer concentration and/or non-solvent greatly influenced the morphology and electrochemical performance of the PE. A conductivity of ∼10<SUP>−3</SUP> S cm<SUP>−1</SUP> and charge/discharge capacities of ∼140 mAh g<SUP>−1</SUP> for the Li/LiFePO<SUB>4</SUB> cell were obtained.</P>
Lithium/Sulfur Secondary Batteries: A Review
Zhao, Xiaohui,Cheruvally, Gouri,Kim, Changhyeon,Cho, Kwon-Koo,Ahn, Hyo-Jun,Kim, Ki-Won,Ahn, Jou-Hyeon The Korean Electrochemical Society 2016 Journal of electrochemical science and technology Vol.7 No.2
Lithium batteries based on elemental sulfur as the cathode-active material capture great attraction due to the high theoretical capacity, easy availability, low cost and non-toxicity of sulfur. Although lithium/sulfur (Li/S) primary cells were known much earlier, the interest in developing Li/S secondary batteries that can deliver high energy and high power was actively pursued since early 1990’s. A lot of technical challenges including the low conductivity of sulfur, dissolution of sulfur-reduction products in the electrolyte leading to their migration away from the cathode, and deposition of solid reaction products on cathode matrix had to be tackled to realize a high and stable performance from rechargeable Li/S cells. This article presents briefly an overview of the studies pertaining to the different aspects of Li/S batteries including those that deal with the sulfur electrode, electrolytes, lithium anode and configuration of the batteries.
Xiaohui Zhao,김둘선,안효준,김기원,진장수,안주현 한국전기화학회 2010 한국전기화학회지 Vol.13 No.3
Sulfur cathodes were prepared by ball milling method with different types of electronic conductors and binders in different ball milling time. The sulfur cell with a cathode prepared in 45 min ball milling time gave an initial discharge capacity of 794mAh/g with Super-P as an electronic conductor and poly(vinylidene fluoride) as a binder. The cathode with multi-walled carbon nanotube as an electronic conductor showed an initial discharge capacity of 944 mAh/g and a discharge capacity of 300 mAh/g after 20 cycles. Cathodes with poly(ethylene oxide) and poly(vinylidene fluoride) as binders showed different cycle performance.
Zhao He,Hongchao Zhao,Jinliang Song,Xiaohui Guo,Zhanjun Liu,Yajuan Zhong,T. James Marrow 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4
Green pitch coke with an average particle size of 2 mm was adopted as densifier and added to the rawmaterials of conventional A3-3 matrix graphite (MG) to prepare modified A3-3 matrix graphite (MMG)by the quasi-isostatic molding method. The structure, mechanical and thermal properties were assessed. Compared with MG, MMG had a more compact structure, and exhibited improved properties of highermechanical strength, higher thermal conductivity and better molten salt barrier performance. Notably,under the same infiltration pressure of 5 atm, the fluoride salt occupation of MMG was only 0.26 wt%,whereas it was 15.82 wt% for MG. The densification effect of green pitch coke endowed MMG withimproved properties for potential use in the spherical fuel elements of molten salt reactor.
Zhao, Xiaohui,Kim, Miso,Liu, Ying,Ahn, Hyo-Jun,Kim, Ki-Won,Cho, Kwon-Koo,Ahn, Jou-Hyeon Elsevier 2018 Carbon Vol.128 No.-
<P><B>Abstract</B></P> <P>A hierarchically porous carbon nanofiber (HPCNF) material was prepared by a facile electrospinning method, with polyvinylpyrrolidone (PVP) as the carbon source and silica formed <I>in-situ</I> as the template. The carbon nanofibers showed a well-designed pore structure: centered macropores are surrounded by a denser cycle consisting of micro-/mesopores near the surface. Sulfur was encapsulated into the pores by solution penetration, followed by a melt diffusion method to generate a flexible sulfur/HPCNF (S/HPCNF) cloth as the binder-free cathode in lithium sulfur (Li-S) batteries. The HPCNF carbon with multi-scaled pores acts as an efficient host for large amounts of sulfur, and accommodates the associated volume expansion during electrochemical cycling. Moreover, the hierarchical architecture significantly reduces the escape of polysulfides during the cycling. The unique material allowed sulfur loading of 2.2–12.1 mg cm<SUP>−2</SUP>, and exhibited a high sulfur utilization of more than 80% with high areal capacity of 11.3 mAh cm<SUP>−2</SUP>, demonstrating that S/HPCNF is a promising cathode material for Li-S batteries of high energy density.</P> <P><B>Graphical abstract</B></P> <P>Root-like porous carbon nanofiber with hierarchical pore system promotes the development of high energy density lithium sulfur batteries.</P> <P>[DISPLAY OMISSION]</P>