• Title/Summary/Keyword: Impedance spectroscopy

Search Result 754, Processing Time 0.03 seconds

Development of the Low Cost Impedance Spectroscopy System for Modeling the Electrochemical Power Sources (전기화학적 전력 기기의 모델링을 위한 저가의 임피던스 분광 시스템의 개발)

  • Lee, Ju-Hyung;Choi, Woo-Jin
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.13 no.1
    • /
    • pp.46-54
    • /
    • 2008
  • In this paper, a low-cost impedance spectroscopy system(LCISS) suitable for modeling the electrochemical power sources such as fuel cells, batteries and supercapacitors is designed and implemented. Since the developed LCISS is composed of simple sensor circuits, commercial data acquisition board and LabVIEW software, a graphic language with powerful HMI(Human-Machine Interface), it is expected ta be widely used in substitution of the expensive EIS instruments. In the proposed system, the digital lock-in amplifier is adopted to achieve the accurate measurements even in the presence of the high level of noises. The developed hardware and software is applied to measure the impedance spectrum of the Ballard Nexa 1.2kW proton exchange membrane fuel cell stack and an equivalent impedance model is proposed based on the measurement results. The validity of the proposed equivalent circuit and the developed system is proven by the measurement of the ac power losses of the PEM fuel celt stack by the ripple current.

CHARACTERISTICS OF LOW-TEMPERATURE PROCESSED DYE-SENSITIZED SOLAR CELL BY ELECTROCHEMICAL IMPEDANCE AND PHOTOCURRENT-PHOTOVOLTAGE TRANSIENT SPECTROSCOPY

  • Li, Yuelong;Lee, Doh-Kwon;Kim, Kyung-Kon;Ko, Min-Jae
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2011.02a
    • /
    • pp.381-381
    • /
    • 2011
  • In this study, a TiO2 colloidal sol was synthesized by sol-gel process, which was used as a "glue" agent to enhance interconnection of TiO2 particles in low temperature process for plastic dye sensitized solar cell. The crystalline phase of this TiO2 glue is pure anatase with average particles size of 5 nm, which was characterized by powder X-ray diffraction and high revolution-TEM. The viscous alcoholic paste without any organic binder was prepared from the mixture of commercial P25 powder and glue. Paste composition and sintering process parameters were optimized for high photovoltaic performance based on low temperature process. The electrochemical impedance spectroscopy and photocurrent-photovoltage transient spectroscopy were also employed to investigate the mechanism of electron transport in this binder free TiO2 film system.

  • PDF

Basic Study for Cone Penetrometer Type Soil Water Content Sensor using Impedance Spectroscopy (원추 관입형 임피던스 수분센서 개발을 위한 기초 연구)

  • Lee, Dong-Hoon;Lee, Kyou-Seung;Chung, Sun-Ok
    • Journal of Biosystems Engineering
    • /
    • v.34 no.6
    • /
    • pp.434-438
    • /
    • 2009
  • This study was conducted to design an cone penetrometer type impedance sensor that can measure soil water content in realtime. The best width between electrical probe was determined by 5 mm. For optimization about realtime application device, linear regression analysis was applied between soil water content and impedance signal. It was concluded that proper combination of excitation frequency, impedance parameter, and model would provide acceptible performance of a soil waler content sensoe. Best model was obatained at a 36.5 MHz with |Z| as a predictor variable, with a coefficient of determination of 0.96 (RMSE=1.35, RPD=4.98).

A Experimental Study on the Evaluation of Anti-corrosion Performance of rebar in concrete added chloride and inhibitor using EIS method (EIS를 이용한 염화물 및 방청제가 첨가된 콘크리트에 매립된 철근의 방식성능 평가에 관한 실험적 연구)

  • Park, Jang-Hyun;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2016.10a
    • /
    • pp.134-135
    • /
    • 2016
  • To evaluate anti-corrosion performance of rebar in concrete according to the amount of chloride and inhibitor, electrochemical impedance spectroscopy(EIS) method was conducted in this study. For the anti-corrosion performance evaluation according to time, Impedance of rebar in concrete was measured before and after 5 cycle of corrosion acceleration. As a results, The impedance of rebar in concrete added chloride decreased than before corrosion acceleration. However impedance of other specimens was maintained or increased than before corrosion acceleration.

  • PDF

Impedance spectroscopy for lifetime analysis of OLED

  • Yoon, Chul-Oh;Kim, Hyun-Chul;Yi, Seok-Kyung;Kong, Ung-Gul;Lee, Nam-Heon;Lee, Chang-Hee
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2002.08a
    • /
    • pp.137-140
    • /
    • 2002
  • The frequency response analysis of complex impedance spectra using small perturbation ac impedance spectroscopy is an informative method of OLED performance characterization and lifetime analysis. Using simple RC equivalent circuit mode,l macroscopic nonliniear transport properties of semiconductive emission/transport layers can be analyzed and parameterized. We present the bias voltage dependence and aging effect in impedance spectra measured from an ITO/CuPC/TPD/$Alq_3$/LiF/Al OLED device, and discuss possible failure mechanism based on impedance model parameters.

  • PDF

Temperature-dependent dielectric relaxation in ITO/Alq3/Al organic light-emitting diodes

  • Ahn, Joonho;Kim, Tae Wan;Lee, Won Jae
    • Journal of Ceramic Processing Research
    • /
    • v.13 no.spc2
    • /
    • pp.163-165
    • /
    • 2012
  • Impedance spectroscopy informs electrical properties of materials as accumulated charges, contact status between electrode and organic materials. We carried out impedance spectroscopy of organic light-emitting diodes as ITO/Alq3(60 nm)/Al on temperatures from 10 K to 300 K. The result described Z'-Z" plot, cole-cole plot and dielectric relaxation time τ. Z'-Z" plot means that real and imaginary part of materials in organic and electrode by frequencies and temperature. Z' as real part of impedance by applied frequency depending on temperature shows the plateau in low frequency region as Rs+ Rp and over 100 kHz in high frequency region as Rs. Cole-cole plot shows resistance of materials in equivalent circuit of the device by temperatures. And equivalent circuit and dielectric relaxation could be accomplished by using the complex impedance analysis.

Investigation on the phase transition of $Ni_2$MnGa alloy by using impedance spectroscopy

  • Park, S.Y.;Cho, K.H.;Lee, Y.P.
    • Journal of Korean Vacuum Science & Technology
    • /
    • v.7 no.1
    • /
    • pp.13-17
    • /
    • 2003
  • The influence of structural transition on the resistance and impedance behavior of Ni$_2$MnGa alloy was investigated. The temperature-dependent resistance and impedance were measured in a temperature range of 4 - 350 K and 185 - 300 K, respectively. The dependence of temperature coefficient of resistivity on temperature shows a kink at 220 K, which is related to the structural transition. The change in dominant scattering mechanism results in the observed kink. Significant increases were also observed around the transition temperature for both real and imaginary parts of impedance. It is thought that this phenomenon originates from disappearance of the martensite twin boundaries during the structural transformation.

  • PDF

Novel State-of-Charge Estimation Method for Lithium Polymer Batteries Using Electrochemical Impedance Spectroscopy

  • Lee, Jong-Hak;Choi, Woo-Jin
    • Journal of Power Electronics
    • /
    • v.11 no.2
    • /
    • pp.237-243
    • /
    • 2011
  • Lithium batteries are widely used in mobile electronic devices due to their higher voltage and energy density, lighter weight and longer life cycle when compared to other secondary batteries. In particular, a high demand for lithium batteries is expected for electric cars. In the case of the lithium batteries used in electric cars, driving distance must be calculated accurately and discharging should not be done below a level that makes it impossible to crank. Therefore, accurate information on the state-of-charge (SOC) becomes an essential element for reliable driving. In this paper, a novel method for estimating the SOC of lithium polymer batteries using AC impedance is proposed. In the proposed method, the parameters are extracted by fitting the measured impedance spectrum on an equivalent impedance model and the variation in the parameter values at each SOC is used to estimate the SOC. Also to shorten the long length of time required for the measurement of the impedance spectrum, a novel method is proposed that can extract the equivalent impedance model parameters of lithium polymer batteries with the impedance measured at only two specific frequencies. Experiments are conducted on lithium polymer batteries, with similar capacities, made by different manufacturers to prove the validity of the proposed method.

Interfacial Electrical/Dielectric Characterization in Low Temperature Polycrystalline Si

  • Hwang, Jin-Ha
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.12 no.1 s.34
    • /
    • pp.77-85
    • /
    • 2005
  • Impedance spectroscopy was applied to low temperature polycrystalline Si in order to investigate the electrical/dielectric information in polycrystalline Si. By combined microstructure and impedance spectroscopy works, it was shown that the electrical information is sensitive to the corresponding microstructure, i.e., the grain size and distribution, judged from the capacitance vs. grain size relationship. At $360 mJ/cm^2$, the maximum in capacitance and the minimum in resistance correspond to the largest grain sizes of unimodal distribution in polycrystalline Si. The electrical/dielectric characterization is compared with Raman spectroscopic characterizations in terms of microstructure.

  • PDF

Effect of $HfO_X$ treatment on ITO surface of organic light emitting diodes using Impedance spectroscopy analysis

  • Cho, Jae-Hyun;Park, Hyung-Jun;Han, Kyu-Min;Sohn, Sun-Young;Jung, Dong-Geun;Yi, Jun-Sin
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.506-508
    • /
    • 2008
  • In this work, we used impedance spectroscopy analysis to determine the effect of the $HfO_X$ treatment on the surface of ITO and to model the equivalent circuit for OLEDs. Devices with an ITO/Organic material/Al structure can be modeled as resistances and capacitances arranged in parallel or in series. The number of elements depends on the composition of the structure, essentially the number of layers, and the contacts.

  • PDF