Flexible, fiber-shaped supercapacitors with roll-type assembly

Yu, Seongil,Patil, Bebi,Ahn, Heejoon THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2019 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.71 No.-

<P><B>Abstract</B></P> <P>A fiber-shaped supercapacitor (FSC) with a unique roll-type configuration is developed by simply rolling polyaniline-coated carbon fiber bundle electrodes with an H<SUB>2</SUB>SO<SUB>4</SUB>/polyvinyl alcohol gel electrolyte. The roll-type polyaniline-coated carbon fibers FSC exhibits four times higher capacitance retention than the twist-type fiber-shaped supercapacitor and shows an energy density of 2.97Whkg<SUP>−1</SUP> at a power density of 4kWkg<SUP>−1</SUP>, which is almost three orders of magnitude higher than that of the twist-type FSC (0.004Whkg<SUP>−1</SUP>). The enhanced performance of the roll-type FSC is attributable to its unique roll-type configuration, which creates a short and consistent distance between the electrodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new roll-type configuration was designed for fiber-shaped supercapacitors (FSCs). </LI> <LI> The roll-type configuration maintains a short distance between the electrodes. </LI> <LI> The roll-type FSC was simply fabricated by roll-up assembly. </LI> <LI> The PANI/CF roll-type FSC exhibited high capacitance retention. </LI> <LI> The roll-type FSC showed excellent mechanical stability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A fiber-shaped supercapacitor (FSC) with a unique roll-type configuration was developed by simply rolling up PANI-coated carbon fiber bundle electrodes and using a PVA–H<SUB>2</SUB>SO<SUB>4</SUB> gel electrolyte. The PANI/CF roll-type FSC exhibited better electrochemical performance than the PANI/CF twist-type FSC.</P> <P>[DISPLAY OMISSION]</P>

PANI//MoO3 Fiber-shaped Asymmetric Supercapacitors with Rolltype Configuration

Seongil Yu,Bebi Patil,안희준 한국섬유공학회 2020 Fibers and polymers Vol.21 No.3

An asymmetric fiber-shaped supercapacitor (FSC) with roll-type configuration, displaying high power and energydensity characteristics, has been fabricated for energy storage in wearable devices. The positive and negative electrodes of theasymmetric FSC consist of polyaniline (PANI) and MoO3, respectively, and are deposited on a carbon fiber (CF) substrateusing a chemical bath deposition method. A polyvinyl alcohol/H2SO4 gel is used as electrolyte, which also maintains the CFelectrodes in fiber form. The asymmetric PANI//MoO3 roll-type FSC exhibits a wider potential range than its symmetricPANI//PANI counterpart, resulting in higher energy and power densities. The asymmetric PANI//MoO3 roll-type FSC showsan energy density of 67.51 μWh/cm3 with a power density of 59.71 mW/cm3 at a current of 10 mA, which is more than twicethe energy density of symmetric PANI//PANI roll-type FSC (30.42 μWh/cm3 and 25.12 mW/cm3).

Synthesis of Bio-based Poly(ethylene 2,5-furandicarboxylate) in a Kneader Reactor and its Melt Spinning

Seongil Yu(유성일),Jae-Chul Lee(이재철),Seungjae Ahn(안승재),Ki-Young Kim(김기영) 한국고분자학회 2020 폴리머 Vol.44 No.5

석유화학물질을 사용하는 것에서 벗어나기 위하여 바이오 기반의 원료를 사용하는 것에 대한 관심이 높아지고 있다. 식물자원으로부터 생산되는 바이오 기반의 원료는 친환경적이며 지속 가능한 자원으로 여겨진다. 현재 널리 사용되고 있는 poly(ethylene terephthalate)(PET)의 대체 후보로 poly(ethylene 2,5-furandicarboxylate)(PEF)가 기대되고 있다. 본 연구는, 플라스크와 kneader 반응기에서 PEF를 중합하여 특성을 비교, 확인하였다. Kneader 반응기에서 효과적으로 PEF를 합성할 수 있었으며, 결과물을 용융 방사한 섬유는 1.80 g/den의 인장강도와, 114.25%의 변형률을 보여주어 PEF를 섬유로 사용할 수 있는 가능성을 확인하였다. There is a growing interest in using bio-based raw materials as a replacement for petrochemical materials. Biobased materials produced from plant resources are considered environmentally sustainable resources. Poly(ethylene 2,5-furandicarboxylate) (PEF) is now widely used and is considered the main substitute for poly(ethylene terephthalate) (PET). In this study, PEF was polymerized in a flask and a kneader reactor, and the properties of PEF were characterized. In the kneader reactor, PEF was synthesized effectively, and the resultant melt-spun fibers with a tensile strength of 1.80 g/den and a strain of 114.25% were obtained, confirming the possibility of utilizing PEF as a fiber.

계통연계형 PV 시스템에서 스트링 Power Optimizer의 Start-up 제어기법

유기범(Gibum Yu),김형진(Hyungjin Kim),하이뜨란(Hai N. Tran),이재연(Jaeyoen Lee),최세완(Sewan Choi),팽성일(Paeng Seongil),주상현(Sanghyun Joo) 전력전자학회 2019 전력전자학술대회 논문집 Vol.2019 No.11

Electrochemical performance of a coaxial fiber-shaped asymmetric supercapacitor based on nanostructured MnO₂/CNT-web paper and Fe₂O₃/carbon fiber electrodes

Patil, Bebi,Ahn, Suhyun,Yu, Seongil,Song, Hyeonjun,Jeong, Youngjin,Kim, Ju Hwan,Ahn, Heejoon Elsevier 2018 Carbon Vol.134 No.-

<P><B>Abstract</B></P> <P>The fiber-shaped supercapacitor is a promising energy storage device in wearable and portable electronics because of its high flexibility, small size, and light weight. However, most of the reported fiber-shaped supercapacitors have exhibited low capacitance and energy density due to the limited surface area between the two fiber electrodes and operating voltage range. Herein, we successfully developed a coaxial fiber-shaped asymmetric supercapacitor (CFASC) made from MnO<SUB>2</SUB>/CNT-web paper as a cathode coupled with Fe<SUB>2</SUB>O<SUB>3</SUB>/carbon fiber as an anode with a high operating voltage of 2.2 V. The prepared CFASC device showed a high volumetric energy density of 0.43 mWh cm<SUP>−3</SUP> at a power density of 0.02 W cm<SUP>−3</SUP>, which is comparable to those of previously reported fiber-shaped supercapacitors. Additionally, CFASC exhibited good rate capability, long cycle life, and high volumetric capacitance (0.67 F cm<SUP>−3</SUP>) with excellent flexibility. The promising performance of CFASC illustrated its potential for portable and wearable energy storage devices.</P> <P><B>Graphical abstract</B></P> <P>The coaxial fiber-shaped asymmetric supercapacitor (CFASC) was successfully developed by simply wrapping the Fe<SUB>2</SUB>O<SUB>3</SUB>/CFs negative electrode with the PVA-LiClO<SUB>4</SUB> gel electrolyte-coated MnO<SUB>2</SUB>/CNT-web paper positive electrode. This CFASC can be operated at large potential windows up to 2.2 V, resulting in high specific energy, and showed excellent cycling stability and device flexibility.</P> <P>[DISPLAY OMISSION]</P>

Interband Transitions in Monolayer and Few-Layer WSe₂ Probed Using Photoexcited Charge Collection Spectroscopy

Choi, Kyunghee,Lee, Kimoon,Yu, Sanghyuck,Oh, Sehoon,Choi, Hyoung Joon,Bae, Heesun,Im, Seongil American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.24

<P>Transition-metal dichalcogenides are currently under rigorous investigation because of their distinct layer-dependent physical properties originating from the corresponding evolution of the band structure. Here, we report the highly resolved probing of layer-dependent band structure evolution for WSe<SUB>2</SUB> using photoexcited charge collection spectroscopy (PECCS). Monolayer, few-layer, and multilayer WSe<SUB>2</SUB> can be probed in top-gate field-effect transistor platforms, and their interband transitions are efficiently observed. Our theoretical calculations show a great coincidence with the PECCS results, proving that the indirect Γ-K and Γ-Λ transitions as well as the direct K-K transition are clearly resolved in multilayer WSe<SUB>2</SUB> by PECCS.</P> [FIG OMISSION]</BR>

Flexible, Swiss roll, fiber-shaped, asymmetric supercapacitor using MnO₂ and Fe₂O₃ on carbon fibers

Cho, Sungdong,Patil, Bebi,Yu, Seongil,Ahn, Suhyun,Hwang, Jeonguk,Park, Changyong,Do, Kwanghyun,Ahn, Heejoon Elsevier 2018 ELECTROCHIMICA ACTA Vol.269 No.-

<P><B>Abstract</B></P> <P>We report a successful demonstration of a Swiss roll, fiber-shaped, asymmetric supercapacitor (FSASC) fabricated with MnO<SUB>2</SUB> as a positive electrode and Fe<SUB>2</SUB>O<SUB>3</SUB> as a negative electrode, both on carbon fibers as the current collector, with a high operating voltage of 2.0 V. The suggested Swiss roll FSASC device exhibited a high gravimetric energy density of 33.1 Wh kg<SUP>−1</SUP> and a volumetric energy density of 0.16 mWh cm<SUP>−3</SUP>, with excellent rate capability, cycling stability, and coulombic efficiency. Additionally, the Swiss roll FSASC showed great durability and flexibility under mechanical stress. The promising performance of the Swiss roll FSASC suggests its potential for applications in wearable and flexible energy storage devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A Swiss roll, fiber-shaped, asymmetric supercapacitor (FSASC) was fabricated via a facile method. </LI> <LI> MnO<SUB>2</SUB>/CFs and Fe<SUB>2</SUB>O<SUB>3</SUB>/CFs were used as the positive and negative electrodes, respectively, in the designed supercapacitor. </LI> <LI> The Swiss roll FSASC showed a high gravimetric energy density of 33.1 Wh kg<SUP>−1</SUP>. </LI> <LI> The Swiss roll FSASC exhibited good rate capability, long cycle life, and excellent flexibility. </LI> <LI> The Swiss roll FSASC maintained electrochemical stability under repeated mechanical stresses. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A Swiss roll, fiber-shaped, asymmetric supercapacitor (FSASC) was successfully fabricated by simply rolling an Fe<SUB>2</SUB>O<SUB>3</SUB>/CF negative electrode and a MnO<SUB>2</SUB>/CF positive electrode with PVA-LiClO<SUB>4</SUB> gel electrolyte. This Swiss roll FSASC can be operated in large potential windows up to 2.0 V and shows excellent rate capability, cycling stability, and device flexibility.</P> <P>[DISPLAY OMISSION]</P>

DNA-based small molecules for hole charge injection and channel passivation in organic heptazole field effect transistors

Cho, Youngsuk,Lee, Junyeong,Lim, June Yeong,Yu, Sanghyuck,Yi, Yeonjin,Im, Seongil IOP 2017 Journal of Physics. D, Applied Physics Vol.50 No.6

<P>DNA-based small molecules of guanine, cytosine, thymine and adenine are adopted for the charge injection layer between the Au electrodes and organic semiconductor, heptazole (C<SUB>26</SUB>H<SUB>16</SUB>N<SUB>2</SUB>). The heptazole-channel organic field effect transistors (OFETs) with a DNA-based small molecule charge injection layer showed higher hole mobility (maximum 0.12 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>) than that of a pristine device (0.09 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>). We characterized the contact resistance of each device by a transfer length method (TLM) and found that the guanine layer among all DNA-based materials performs best as a hole injection layer leading to the lowest contact resistance. Since the guanine layer is also known to be a proper channel passivation layer coupled with a thin conformal Al<SUB>2</SUB>O<SUB>3</SUB> layer protecting the channel from bias stress and ambient molecules, we could realize ultra-stable OFETs utilizing guanine/Au contact and guanine/Al<SUB>2</SUB>O<SUB>3</SUB> bilayer on the organic channel.</P>

Facile Low-temperature Chemical Synthesis and Characterization of a Manganese Oxide/multi-walled Carbon Nanotube Composite for Supercapacitor Applications

Jang, Kihun,Lee, Sung-Won,Yu, Seongil,Salunkhe, Rahul R.,Chung, Ildoo,Choi, Sungmin,Ahn, Heejoon Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.10

$Mn_3O_4$/multi-walled carbon nanotube (MWCNT) composites are prepared by chemically synthesizing $Mn_3O_4$ nanoparticles on a MWCNT film at room temperature. Structural and morphological characterization has been carried out using X-ray diffraction (XRD) and scanning and transmission electron microscopies (SEM and TEM). These reveal that polycrystalline $Mn_3O_4$ nanoparticles, with sizes of about 10-20 nm, aggregate to form larger nanoparticles (50-200 nm), and the $Mn_3O_4$ nanoparticles are attached inhomogeneously on MWCNTs. The electrochemical behavior of the composites is analyzed by cyclic voltammetry experiment. The $Mn_3O_4$/MWCNT composite exhibits a specific capacitance of $257Fg^{-1}$ at a scan rate of $5mVs^{-1}$, which is about 3.5 times higher than that of the pure $Mn_3O_4$. Cycle-life tests show that the specific capacitance of the $Mn_3O_4$/MWCNT composite is stable up to 1000 cycles with about 85% capacitance retention, which is better than the pure $Mn_3O_4$ electrode. The improved supercapacitive performance of the $Mn_3O_4$/MWCNT composite electrode can be attributed to the synergistic effects of the $Mn_3O_4$ nanoparticles and the MWCNTs, which arises not only from the combination of pseudocapacitance from $Mn_3O_4$ nanoparticles and electric double layer capacitance from the MWCNTs but also from the increased surface area, pore volume and conducting property of the MWCNT network.

Simple, ultra-rapid, versatile method to synthesize cobalt/cobalt oxide nanostructures on carbon fiber paper via intense pulsed white light (IPWL) photothermal reduction for energy storage applications

Lee, Sanghyun,Park, Sung-Hyeon,Jang, Kihun,Yu, Seongil,Song, Chiho,Kim, Hak-Sung,Ahn, Heejoon Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.724 No.-

<P><B>Abstract</B></P> <P>Cobalt-based nanomaterials have received considerable attention in electric energy-storage devices due to their outstanding electrochemical characteristics. However, multiple time- and energy-consuming steps and complex reduction processes for producing cobalt and cobalt oxide nanostructures are disrupting their substantive commercialization. Here, we propose a facile, ultra-fast, and versatile method for the fabrication of cobalt and cobalt oxide nanostructures using an intense pulsed white light (IPWL) photothermal reduction technique. The mechanism of the IPWL photothermal reduction of cobalt and cobalt oxide is firstly studied by measuring the in-situ temperature of the Co(NO<SUB>3</SUB>)<SUB>2</SUB>-coated carbon fiber paper (CFP) substrate during IPWL irradiation and analyzing the crystal structures of the IPWL-irradiated samples. Cobalt nanoflakes and cobalt oxide nanoparticles are synthesized on the surface of the CFP substrate by irradiating IPWL for 10 ms at ambient temperature and pressure with various energy densities from 10 to 30 J cm<SUP>−2</SUP>. The Co<SUB>3</SUB>O<SUB>4</SUB> nanoparticle/CFP and Co nanoflake/CFP samples are further utilized as an electrode, and each electrode exhibits high specific capacity of 29 and 73 mA h g<SUP>−1</SUP>, respectively, at a current density of 1 A g<SUP>−1</SUP>. Since this novel photothermal reduction technique is applicable to other transition metals and metal oxides, it is a promising method for not only energy storage systems, but also for energy generation applications, filters, sensors, and catalysis systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile, ultra-fast, versatile IPWL photothermal reduction technique is proposed. </LI> <LI> Co nanoflakes and cobalt oxide nanoparticles are fabricate on CFP by IPWL. </LI> <LI> The mechanism of the IPWL photothermal reduction of cobalt/cobalt oxide is studied. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The intense pulsed white light (IPWL) photothermal reduction process enables ultra-rapid and facile synthesis of cobalt nanoflakes and cobalt oxide nanoparticles on carbon fiber paper (CFP). The IPWL-induced Co<SUB>3</SUB>O<SUB>4</SUB> nanoparticle/CFP and Co nanoflake/CFP electrodes exhibit high specific capacity, as well as excellent rate capability and cycle stability.</P> <P>[DISPLAY OMISSION]</P>