The Experts below are selected from a list of 11904 Experts worldwide ranked by ideXlab platform

Bernard Davat - One of the best experts on this subject based on the ideXlab platform.

  • contributions of fractional differentiation to the modelling of Electric Double Layer capacitance
    2010
    Co-Authors: Idris Sadli, Matthieu Urbain, Melika Hinaje, Jeanphilippe Martin, Stephane Rael, Bernard Davat
    Abstract:

    Abstract The Electric Double Layer phenomenon is sometimes described by means of a specific element called “constant phase element”, instead of the usual Electric Double Layer capacitance. This article deals with such an element, often associated with rough surfaces. It is first shown, using a lithium–ion battery and a PEM fuel cell, that this element can obviously improve accuracy in the modelling of electrochemical device harmonic spectrum. The article then focuses on an approximation method, which enables easy use of constant phase element in time domain. This method, which comes from fractional differentiation theory, is based on some properties of recursive transfer functions. The approximation procedure is explained, and comparisons between exact and approximated results are carried out.

  • A physical based model of power Electric Double-Layer supercapacitors
    2000
    Co-Authors: Farid Belhachemi, Stephane Rael, Bernard Davat
    Abstract:

    Recent developments in the field of supercapacitors have led to the achievement of high specific and high power density devices. With capacities of several hundred farads and serial resistances less than one milliohm, these new components are suitable for energy storage in high power electronic applications, especially in the field of management of embarked Electrical power (hybrid power sources, energy recovery). This paper deals with investigations, including theory, characterisation and experimental validation, on an accurate Electric Double-Layer supercapacitor modelling based on the physics of phenomena governing charges storage, which theoretically leads to a transmission line with voltage dependant distributed capacitance.

  • a physical based model of power Electric Double Layer supercapacitors
    2000
    Co-Authors: Farid Belhachemi, Stephane Rael, Bernard Davat
    Abstract:

    Recent developments in the field of supercapacitors have led to the achievement of high specific energy and high specific power devices. Due to capacitances of several hundred farads and serial resistances of less than one milliohm, these new components are suitable for energy storage in high power electronic applications, especially in the field of management of embarked Electrical power (hybrid power sources, energy recovery). This paper presents the theory, characterisation and experimental validation of an accurate Electric Double-Layer supercapacitor model based on the physics of phenomena governing charges storage, which theoretically leads to a transmission line with voltage dependant distributed capacitance.

Yoshikazu Nakayama - One of the best experts on this subject based on the ideXlab platform.

  • vertically aligned Double walled carbon nanotube electrode prepared by transfer methodology for Electric Double Layer capacitor
    2008
    Co-Authors: Yuichi Honda, Masayuki Takeshige, Hideki Shiozaki, Takaharu Kitamura, Kenji Yoshikawa, Supriya Chakrabarti, Osamu Suekane, Lujun Pan, Yoshikazu Nakayama
    Abstract:

    Abstract We successfully prepared a vertically aligned Double-walled carbon nanotube (DWCNT) sheet by a transfer procedure from a silicon substrate as a DWCNT seedbed that was covered with catalyst grains to an aluminum sheet as a current collector for application to a high-performance electrode for an Electric Double Layer capacitor (EDLC). The charge–discharge characteristics and EDLC performances of the aligned DWCNT electrode were evaluated and compared with those of a vertically aligned multi-walled CNT (MWCNT) electrode. The gravimetric capacitance of the DWCNT electrode was ca. four times larger than that of the MWCNT electrode. The rate capability of the DWCNT electrode was found to be excellent. This is mainly ascribed to our transfer technique.

Yoshihiro Iwasa - One of the best experts on this subject based on the ideXlab platform.

  • improved performance of a gamnas based vertical spin Electric Double Layer transistor
    2018
    Co-Authors: Toshiki Kanaki, Yoshihiro Iwasa, Hiroki Yamasaki, Hiroshi Terada, Shinobu Ohya, Masaaki Tanaka
    Abstract:

    A spin metal–oxide–semiconductor field-effect transistor (MOSFET) is a promising spintronics device for future low-power electronics. In this paper, we demonstrate the successful improvement of the performance of a spin-MOSFET-type device, a ferromagnetic-semiconductor GaMnAs-based vertical spin Electric Double-Layer transistor (EDLT); the magnetoresistance ratio reaches 37%, which is 7 times larger than those obtained in previous studies. Furthermore, we find that the magnetic anisotropy of our device is modulated by changing the gate voltage. Our results open up the possibility of realizing novel functional devices, in which both current and magnetic anisotropy can be controlled by the gate Electric field.

  • large area wse2 Electric Double Layer transistors on a plastic substrate
    2015
    Co-Authors: Kazuma Funahashi, Yoshihiro Iwasa, Taishi Takenobu
    Abstract:

    Due to the requirements for large-area, uniform films, currently transition metal dichalcogenides (TMDC) cannot be used in flexible transistor industrial applications. In this study, we first transferred chemically grown large-area WSe2 monoLayer films from the as-grown sapphire substrates to the flexible plastic substrates. We also fabricated Electric Double Layer transistors using the WSe2 films on the plastic substrates. These transistors exhibited ambipolar operation and an ON/OFF current ratio of ~104, demonstrating chemically grown WSe2 transistors on plastic substrates for the first time. This achievement can be an important first step for the next-generation TMDC based flexible devices.

  • field induced superconductivity in Electric Double Layer transistors
    2014
    Co-Authors: H. Shimotani, Yoshihiro Iwasa, Masashi Kawasaki, Hongtao Yuan, Kazunori Ueno
    Abstract:

    Electric field tuning of superconductivity has been a long-standing issue in solid state physics since the invention of the field-effect transistor (FET) in 1960. Owing to limited available carrier density in conventional FET devices, Electric-field-induced superconductivity was believed to be possible in principle but impossible in practice. However, in the past several years, this limitation has been overcome by the introduction of an electrochemical concept, and Electric-field-induced superconductivity has been realized. In the Electric Double Layer (EDL) formed at the electrochemical interfaces, an extremely high Electric field is generated and hence high-density charge carriers sufficient to induce superconductivity exist and are collectively used as a charge accumulation device known as an EDL capacitor. Field-induced superconductivity has been used to establish the relationship between Tc and carrier density and can now be used to search for new superconductors. Here, we review Electric-field-induc...

  • liquid gated Electric Double Layer transistor on Layered metal dichalcogenide sns2
    2011
    Co-Authors: Hongtao Yuan, H. Shimotani, M Toh, Kazuhiro Morimoto, W Tan, Fengxia Wei, Ch Kloc, Yoshihiro Iwasa
    Abstract:

    With ionic liquid (IL) gating in Electric-Double-Layer transistors (EDLTs), we report field effect operation and electronic state modulation in a Layered material of SnS2, demonstrating that the EDLT is applicable to modifying the electronic properties of metal dichalcogenides. The IL-gated SnS2 EDLTs allow us to realize high performance transistor operation and to achieve interfacial carrier accumulation to a level as high as 5.4×1014 cm−2, as quantitatively estimated from the Hall effect. A considerable decrease of the activation energy in temperature-dependent sheet resistance implies that liquid gating is an effective way to tune the electronic states of metal dichalcogenides at EDL interfaces.

  • Electric Double Layer transistor of organic semiconductor crystals in a four probe configuration
    2007
    Co-Authors: H. Shimotani, Haruhiko Asanuma, Yoshihiro Iwasa
    Abstract:

    Electric Double Layer field-effect transistors (EDL-FETs) of rubrene single crystals using a liquid polymer electrolyte were studied in a four-probe configuration. The channel sheet resistance and the contact resistance normalized by the contact width were 0.24 MΩ and 0.83 kΩ cm in the ON-state, respectively. These values are smaller than those of previously reported conventional rubrene crystal FETs, corroborating the high carrier density accumulation in the EDL-FET. In addition, peculiar peak behaviour in the transfer characteristics did not appear in the gate voltage dependence of four-probe conductivity. This observation leads us to conclude that the peak is ascribed to the increase of the contact resistance in the high gate voltage region.

R Santamaria - One of the best experts on this subject based on the ideXlab platform.

  • redox active electrolyte for carbon nanotube based Electric Double Layer capacitors
    2011
    Co-Authors: Silvia Roldan, Zoraida Gonzalez, C Blanco, M Granda, R Menendez, R Santamaria
    Abstract:

    Abstract The specific capacitance of the MWCNTs was improved by the addition of an electrochemically active compound (indigo carmine) to an electrolyte generally used in Electric Double Layer capacitors. The pseudocapacitive contribution of the IC trebled the specific capacitance values of the MWCNTs at low current densities (from 17 Fg −1 to 50 Fg −1 ). The good resistance obtained for the MWCNT-based capacitor was not modified with the use of this novel redox-active electrolyte. A reversible process associated to the redox reaction of IC was found to be responsible for the capacitance increase observed. Therefore, a combined effect of Double Layer formation and pseudocapacitive phenomena is presented. Long-term cycling experiments performed showed good stability with a reduction of the initial capacitance values of 30% after 10,000 galvanostatic cycles at 360 mAg −1 . The efficiency of the cell was close to 100% throughout the experiment.

Yusheng Yang - One of the best experts on this subject based on the ideXlab platform.

  • room temperature molten salt as electrolyte for carbon nanotube based Electric Double Layer capacitors
    2006
    Co-Authors: Renjie Chen, Gaoping Cao, Shi Chen, Guoqing Wang, Yusheng Yang
    Abstract:

    Abstract Electric Double Layer capacitors (EDLCs) have been assembled with carbon nanotubes (CNTs) as the electrodes and a novel binary room temperature molten salt (RTMS) composed of lithium bis(trifluoromethane sulfone)imide (LiN(SO2CF3)2, LiTFSI) and acetamide as the electrolyte. The electrochemical performances of the RTMS and the EDLC are evaluated with cyclic voltammetry (CV), ac impedance spectroscopy and galvanostatic charge/discharge, etc. The EDLC with these components show excellent electrochemical properties in specific capacitance, rate and cycling performances at ambient and elevated (60 °C) temperatures, indicating that RTMS is a promising electrolyte for advanced EDLCs.