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Synthesis and electrochemical properties of polyaniline nanofibers by interfacial polymerization.
Manuel, James,Ahn, Jou-Hyeon,Kim, Dul-Sun,Ahn, Hyo-Jun,Kim, Ki-Won,Kim, Jae-Kwang,Jacobsson, Per American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.4
<P>Polyaniline nanofibers were prepared by interfacial polymerization with different organic solvents such as chloroform and carbon tetrachloride. Field emission scanning electron microscopy and transmission electron microscopy were used to study the morphological properties of polyaniline nanofibers. Chemical characterization was carried out using Fourier transform infrared spectroscopy, UV-Vis spectroscopy, and X-ray diffraction spectroscopy and surface area was measured using BET isotherm. Polyaniline nanofibers doped with lithium hexafluorophosphate were prepared and their electrochemical properties were evaluated.</P>
Surface-modified polyethylene separator via oxygen plasma treatment for lithium ion battery
진소연,James Manuel,Xiaohui Zhao,박원호,안주현 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.45 No.-
The separator is an important component in lithium ion batteries (LIBs). However, commercialseparators such as polyethylene (PE) and polypropylene (PP) are in urgent need to be modified toimprove the surface properties to meet requirements for high performance LIBs. In this study, oxygenplasma has been applied tomodify the surface of PE separating membrane with functional groups, whichhas greatly improved the electrolyte wettability and retention of PE separators. The cells with plasmatreatedPE separators showed improved charge–discharge capability with lower interfacial resistanceand stable cycling performance. This result demonstrates a high potential of the plasma-treated PEseparator in LIBs.
Shin, Chorong,Manuel, James,Kim, Dul-Sun,Ryu, Ho-Suk,Ahn, Hyo-Jun,Ahn, Jou-Hyeon Springer 2012 Nanoscale research letters Vol.7 No.1
<P>Cobalt oxide [Co<SUB>3</SUB>O<SUB>4</SUB>] anode materials were synthesized by a simple hydrothermal process, and the reaction conditions were optimized to provide good electrochemical properties. The effect of various synthetic reaction and heat treatment conditions on the structure and electrochemical properties of Co<SUB>3</SUB>O<SUB>4 </SUB>powder was also studied. Physical characterizations of Co<SUB>3</SUB>O<SUB>4 </SUB>are investigated by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller [BET] method. The BET surface area decreased with values at 131.8 m<SUP>2</SUP>/g, 76.1 m<SUP>2</SUP>/g, and 55.2 m<SUP>2</SUP>/g with the increasing calcination temperature at 200°C, 300°C, and 400°C, respectively. The Co<SUB>3</SUB>O<SUB>4 </SUB>particle calcinated at 200°C for 3 h has a higher surface area and uniform particle size distribution which may result in better sites to accommodate Li<SUP>+ </SUP>and electrical contact and to give a good electrochemical property. The cell composed of Super P as a carbon conductor shows better electrochemical properties than that composed of acetylene black. Among the samples prepared under different reaction conditions, Co<SUB>3</SUB>O<SUB>4 </SUB>prepared at 200°C for 10 h showed a better cycling performance than the other samples. It gave an initial discharge capacity of 1,330 mAh/g, decreased to 779 mAh/g after 10 cycles, and then showed a steady discharge capacity of 606 mAh/g after 60 cycles.</P>
유형민,이종화,( James Manuel ),김미소,( Ying Liu ),( Ghanshyam S Chauhan ),박원호,안주현 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
A separator plays an important role to achieve good battery performance with stable cycle life, high energy density, high rate capability, and safety in lithium ion batteries (LIBs). Currently, polyolefin microporous membranes are commonly used as the separator in commercial LIBs due to their good chemical stability and high mechanical strength. However, some of their intrinsic properties, such as low porosity and poor wettability with polar liquid electrolyte, which affect cell resistance, energy density, and rate capability of LIB, should be improved. One of the effective approaches to overcome these limitations is to fabricate a separator using a thermally stable polymer by electrospinning technique. In this work, we have prepared polyacrylonitrile (PAN) nanofibrous membranes by electrospinning technique and those were converted to partially oxidized PAN (oxy-PAN) by heating at 230℃ in air for different time periods. Thus prepared oxy-PAN membranes showed good electrolyte wettability, high ionic conductivity, uniform tensile strength, excellent thermal stability and stable cycle performance in LIBs.
Lee, Jong Hwa,Manuel, James,Choi, Hyunji,Park, Won Ho,Ahn, Jou-Hyeon Elsevier 2015 Polymer Vol.68 No.-
<P><B>Abstract</B></P> <P>Nanofibrous membranes of polyacrylonitrile (PAN) prepared by electrospinning technique were converted to partially oxidized PAN (oxy-PAN) at 230 °C and at different time periods. The physical properties and electrochemical characteristics of oxy-PAN membranes were investigated for use as separator membrane in lithium ion battery (LIB). The optimized oxy-PAN membrane showed high tensile strength and thermal stability along with high electrolyte uptake and high ionic conductivity at room temperature. Impedance spectroscopic studies of oxy-PAN membranes revealed good stability and compatibility with lithium electrode and liquid electrolyte which are favorable attributes for long-term storage of lithium ion batteries. The Li/oxy-PAN/LiFePO<SUB>4</SUB> cell delivered stable and excellent cycle performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electrospun nanofibrous membrane of PAN was prepared. </LI> <LI> Partial oxidation was carried out to enhance mechanical stability. </LI> <LI> Oxy-PAN membranes show high tensile strength and good electrochemical performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>