http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Veerasubramani, Ganesh Kumar,Park, Myung-Soo,Nagaraju, Goli,Kim, Dong-Won The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.42
<P>Achieving hierarchically uniform surface manipulated nanostructured materials is important to accomplish high performance storage devices, but it is still challenging. Herein, we successfully synthesized a vertically-aligned interlayer-expanded caterpillar-like heterostructure consisting of MoS2@C nanosheets (NSs) over MoS2 nanorods (NRs) (MoS2@C@MoS2) as an advanced anode material for sodium-ion batteries (SIBs). Step-wise ramp rate tuned MoS2 nanorods (NRs) were achieved <I>via</I> surface sulfurization of MoO3 NRs by a vapor phase ion-exchange method. Heterointerphased MoS2@C nanosheets performed a crucial role in enacting an excellent electrochemical performance by facilitating better Na<SUP>+</SUP> ion diffusion and faster electron transport. The hierarchical MoS2@C@MoS2 electrode delivered a high specific capacity of 434 mA h g<SUP>−1</SUP> (after 100 cycles at 100 mA g<SUP>−1</SUP>) and excellent cycling stability (352 mA h g<SUP>−1</SUP> after 200 cycles at 1000 mA g<SUP>−1</SUP>). Kinetic analysis revealed that an enhanced sodium storage performance of the MoS2@C@MoS2 electrode could be accompanied by an ameliorated capacitive contribution reaction. Moreover, the sodium-ion full cell assembled with the MoS2@C@MoS2 anode and a Na3V2(PO4)2F3 cathode exhibited a high specific capacity of 320 mA h g<SUP>−1</SUP> with good capacity retention.</P>
Veerasubramani, Ganesh Kumar,Subramanian, Yuvaraj,Park, Myung-Soo,Senthilkumar, Baskar,Eftekhari, Ali,Kim, Sang Jae,Kim, Dong-Won Elsevier 2019 ELECTROCHIMICA ACTA Vol.296 No.-
<P><B>Abstract</B></P> <P>Integration of P2 and O3 phases in Na<SUB>0.5</SUB>Fe<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>2</SUB> cathode via Li-ion substitution is proposed to enhance its electrochemical performance for sodium-ion battery applications. The formation of P2 and the combination of P2/O3 intergrowth were confirmed by X-ray diffraction refinement, high resolution transmission electron microscopy and X-ray photoelectron microscopy analyses. Various content of lithium was used to find optimum P2+O3 combinations. The optimized Li-ion substituted Na<SUB>0.5</SUB>(Li<SUB>0.10</SUB>Fe<SUB>0.45</SUB>Mn<SUB>0.45</SUB>)O<SUB>2</SUB> showed a high initial discharge capacity of 146.2 mAh g<SUP>−1</SUP> with improved cycling stability, whereas the pristine Na<SUB>0.5</SUB>Fe<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>2</SUB> initially delivered a discharge capacity of 127.0 mAh g<SUP>−1</SUP>. In addition, the combination of P2+O3 increased its average voltage, which is important for achieving high energy density sodium-ion batteries. Overall, the prepared Na<SUB>0.5</SUB>(Li<SUB>0.10</SUB>Fe<SUB>0.45</SUB>Mn<SUB>0.45</SUB>)O<SUB>2</SUB> electrode exhibited the improved cycling performance in terms of reversible capacity and rate capability compared to pristine Na<SUB>0.5</SUB>Fe<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>2</SUB> electrode material.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile sol-gel route is used to synthesis of layered cathode via Li-ion substitution. </LI> <LI> Combination of P2 and O3 phases is confirmed using XRD refinement results. </LI> <LI> P2+O3 Na<SUB>0.5</SUB>[Li<SUB>0.10</SUB>Fe<SUB>0.45</SUB>Mn<SUB>0.45</SUB>]O<SUB>2</SUB> biphasic cathode exhibits good cycling performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Veerasubramani, Ganesh Kumar,Krishnamoorthy, Karthikeyan,Pazhamalai, Parthiban,Kim, Sang Jae Elsevier 2016 Carbon Vol.105 No.-
<P>The flexible cable/wire type supercapacitors are attracting more attentions as the power supply in wearable electronics. Herein, we report the flexible cable-type supercapacitor (FCSC) using hydrothermally reduced graphene oxide (rGO) nanosheets and successfully improved their electrochemical performances using redox additive electrolyte. The synthesized rGO nanosheets are well characterized in both structural and electrochemical parts. The fabricated FCSC device works up to 1 V without any evolution occurred, and exhibits excellent electrochemical performances. Further, the performances of FCSC are improved more than three times using sodium molybdate (Na2MoO4) as redox additive electrolyte. The addition of Na2MoO4 in polymer gel electrolyte for rGO based FCSC exhibits a maximum length capacitance and energy density of 18.75 mF cm(-1) (areal capacitance of 38.2 mF cm(-2)) and 2.6 mWh cm(-1) (areal energy density of 5.3 mWh cm(-2)) respectively. The detailed mechanism has been explored for these improved electrochemical activities. The flexibility and stability of the FCSC device have been investigated and three serially connected devices are capable of lit up the green and blue LEDs. Overall, these findings could open up a simple and cost effective approach to improve the performances of carbon materials in the field of flexible energy storage applications. (C) 2016 Elsevier Ltd. All rights reserved.</P>
Effective use of an idle carbon-deposited catalyst for energy storage applications
Veerasubramani, G.,Sudhakaran, M. S.,Alluri, N.,Krishnamoorthy, K.,Mok, Y.,Kim, S. Royal Society of Chemistry 2016 Journal of Materials Chemistry A Vol.4 No.32
<P>Global warming is primarily a problem of excessive carbon dioxide (CO2) in the atmosphere, which acts as a blanket, trapping heat and warming the planet. One of the inevitable reactions during syngas (SNG) production by the dry reforming reaction (DRR) of hydrocarbons is the deposition of carbon over the catalyst which can be eliminated as anthropogenic CO2. This is the main obstacle for SNG production during the DRR, diminishes the performance of the catalysts and enhances the CO2 formation which leads to global warming. In this study, for the first time, we present a novel approach to use the carbondeposited catalyst formed during the DRR as an effective electrode material for supercapacitor applications. This disposable carbon- deposited catalyst shows similar to 22 times higher capacity than the bare catalyst and acts as a positive electrode for asymmetric supercapacitors. The fabricated supercapacitor device works with an extended voltage of 1.6 V and exhibits an excellent electrochemical performance. Moreover, serially connected supercapacitor devices could power up various types of LEDs and UV light sensors.</P>
Veerasubramani, G.K.,Krishnamoorthy, K.,Kim, S.J. Elsevier Sequoia 2016 Journal of Power Sources Vol.306 No.-
Herein, we are successfully prepared cobalt molybdate (CoMoO<SUB>4</SUB>) grown on nickel foam as a binder free electrode by hydrothermal approach for supercapacitors and improved their electrochemical performances using potassium ferricyanide (K<SUB>3</SUB>Fe(CN)<SUB>6</SUB>) as redox additive. The formation of CoMoO<SUB>4</SUB> on Ni foam with high crystallinity is confirmed using XRD, Raman, and XPS measurements. The nanoplate arrays (NPAs) of CoMoO<SUB>4</SUB> are uniformly grown on Ni foam which is confirmed by FE-SEM analysis. The prepared binder-free CoMoO<SUB>4</SUB> NPAs achieved maximum areal capacity of 227 μAh cm<SUP>-2</SUP> with KOH electrolyte at 2.5 mA cm<SUP>-2</SUP>. This achieved areal capacity is further improved about three times using the addition of K<SUB>3</SUB>Fe(CN)<SUB>6</SUB> as redox additive. The increased electrochemical performances of CoMoO<SUB>4</SUB> NPAs on Ni foam electrode via redox additive are discussed in detail and the mechanism has been explored. Moreover, the assembled CoMoO<SUB>4</SUB> NPAs on Ni foam//activated carbon asymmetric supercapacitor device with an extended operating voltage window of 1.5 V exhibits an excellent performances such as high energy density and cyclic stability. The overall performances of binder-free CoMoO<SUB>4</SUB> NPAs on Ni foam with redox additives suggesting their potential use as positive electrode material for high performance supercapacitors.
Synthesis, characterization, and electrochemical properties of CoMoO<sub>4</sub> nanostructures
Veerasubramani, G.K.,Krishnamoorthy, K.,Radhakrishnan, S.,Kim, N.J.,Kim, S.J. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.10
We report a facile sonochemical approach for the synthesis of cobalt molybdate (CoMoO<SUB>4</SUB>) nanostructures and their application as electrodes for supercapacitors. X-ray diffraction analysis showed the formation of monoclinic CoMoO<SUB>4</SUB>. The surface morphology was investigated using a field-emission scanning electron microscope, which showed the formation of plate-like CoMoO<SUB>4</SUB> nanostructures. The growth mechanism and formation of the CoMoO<SUB>4</SUB> nanostructures is discussed. Further, the electrochemical performance of the CoMoO<SUB>4</SUB> nanostructures was examined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge analysis. The CV curves showed the presence of redox pairs and, along with the EIS data (using Nyquist and Bode plots), demonstrated the pseudocapacitance nature of the synthesized CoMoO<SUB>4</SUB>. The galvanostatic studies showed non-symmetric discharge curves, and a maximum specific capacitance of ~133 F g<SUP>-1</SUP> was obtained at a constant discharge current density (1 mA cm<SUP>-2</SUP>). The cyclic stability tests demonstrated capacitance retention of about 84% after 1000 cycles, suggesting the potential application of CoMoO<SUB>4</SUB> in energy-storage devices.
VEERASUBRAMANI GANESH KUMAR,KRISHNAMOORTHYKARTHIKEYAN,SIVAPRAKASAMRADHAKRISHNAN,김남진,김상재 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.36 No.-
A simple and green approach for the preparation of cobalt molybdate/polyaniline (CoMoO4/PANI)composite via in-situ polymerization method has been reported. The growth of PANI conductive layer onthe surface of plate-like CoMoO4 nanostructures has been confirmed by XRD, FT-IR, Raman and FE-SEMtechniques. The prepared CoMoO4/PANI composite delivered a maximum specific capacitance of 246 F/gat scan rate of 5 mV/s, whereas pristine PANI exhibits only 160 F/g which attributed to the synergic effecton the conducting network between CoMoO4 and PANI. The cyclic stability measurement revealed thatabove 80% of its initial capacitance is retained even after long cycles.
Veerasubramani, Ganesh Kumar,Subramanian, Yuvaraj,Park, Myung-Soo,Nagaraju, Goli,Senthilkumar, Baskar,Lee, Yun-Sung,Kim, Dong-Won The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.41
<P>Sodium-ion batteries (SIBs) are undoubtedly the most promising alternatives to lithium-ion batteries considering the natural abundance, distribution and cost of sodium resources. Still, SIBs face challenges in the development of suitable anode materials due to the large volume change during sodiation/de-sodiation, which results in inferior cycling stability. Herein, we synthesized a yolk-shell structured pyrrhotite (Fe1−xS)@N-doped carbon (FS@NC) through a solution-based method and investigated its electrochemical properties for use in SIBs as an anode material. The optimized yolk-shell structured FS@NC with distinctive voids and a core exhibited a high reversible capacity of 594 mA h g<SUP>−1</SUP> over 100 cycles at 100 mA g<SUP>−1</SUP>, excellent rate capability and superior cycling performance compared to core-shell and pristine Fe1−xS materials. During the charge and discharge cycles, the synergistic effect of the porous core (Fe1−xS) with empty voids and a defective carbon shell configuration provided a large electrode/electrolyte contact area and shortened the diffusion path for electrons and sodium ions. It also mitigated the structural degradation by accommodating the volume change during continuous cycles, which was confirmed by <I>ex situ</I> SEM and TEM analyses. To demonstrate a practical application, we assembled a sodium-ion full cell with an O3-type NaCo0.5Fe0.5O2 cathode and a yolk-shell structured FS@NC anode, and the results showed superior energy storage performance.</P>
Veerasubramani, G.K.,Krishnamoorthy, K.,Radhakrishnan, S.,Kim, N.J.,Kim, S.J. Korean Society of Industrial and Engineering Chemi 2016 Journal of industrial and engineering chemistry Vol.36 No.-
<P>A simple and green approach for the preparation of cobalt molybdate/polyaniline (CoMoO4/PANI) composite via in-situ polymerization method has been reported. The growth of PANI conductive layer on the surface of plate-like CoMoO4 nanostructures has been confirmed by XRD, FT-IR, Raman and FE-SEM techniques. The prepared CoMoO4/PANI composite delivered a maximum specific capacitance of 246 F/g at scan rate of 5 mV/s, whereas pristine PANI exhibits only 160 F/g which attributed to the synergic effect on the conducting network between CoMoO4 and PANI. The cyclic stability measurement revealed that above 80% of its initial capacitance is retained even after long cycles. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>