An investigation of the capacitance dispersion on the fractal carbon electrode with edge and basal orientations

Kim, Chang-Hee; Pyun, Su‐Il; Kim, Jong-Huy

doi:10.1016/s0013-4686(03)00464-x

Cited by 187 publications

(103 citation statements)

References 19 publications

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“…Implementation of blocking conditions may be realized by using a salt which cannot react electrochemically with the electrodes within the potential excitation of a few mV during an impedance measurement. In reality, surface roughness 37 or an inhomogeneous current distribution 38 may alter the ideally polarizable behavior of electrodes, and a blocking electrode is therefore generally described best by a constant-phase Element (CPE), the complex impedance of which is given as…”

Section: Theorymentioning

confidence: 99%

Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy

Landesfeind

Hattendorff

Ehrl

et al. 2016

J. Electrochem. Soc.

486

596

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Lithium ion battery performance at high charge/discharge rates is largely determined by the ionic resistivity of an electrode and separator which are filled with electrolyte. Key to understand and to model ohmic losses in porous battery components is porosity as well as tortuosity. In the first part, we use impedance spectroscopy measurements in a new experimental setup to obtain the tortuosities and MacMullin numbers of some commonly used separators, demonstrating experimental errors of <8%. In the second part, we present impedance measurements of electrodes in symmetric cells using a blocking electrode configuration, which is obtained by using a non-intercalating electrolyte. The effective ionic resistivity of the electrode can be fit with a transmission-line model, allowing us to quantify the porosity dependent MacMullin numbers and tortuosities of electrodes with different active materials and different conductive carbon content. Best agreement between the transmission-line model and the impedance data is found when constant-phase elements rather than simple capacitors are used. Motivation.-Advanced battery models are a valuable tool for evaluating the performance, safety, and life-time of lithium ion batteries, since they can provide insight into the kinetics and the transport characteristics of batteries, which are not or only partially accessible by experiments. To obtain quantitative and meaningful numerical results, the choice of appropriate physical models and boundary conditions with the corresponding, accurately determined, kinetic and transport parameters are key issues. For numerical simulations of battery systems, the ion-transport model for concentrated electrolyte solutions introduced by Newman et al.1 is frequently used. Since the microscopic geometry of actually used porous electrodes and separators are largely unknown, a homogenization approach is applied for the macroscopic description of porous media. In this case, the influence of the microstructure on the macroscopic behavior is modeled by additional geometric parameters such as the porosity ε and the tortuosity τ. The porosity ε is a well-defined property of a porous medium, which can be determined easily. In contrast, the effective tortuosity of separators and particularly of electrodes are more difficult to quantify, and, to further complicate the matter, many different definitions for the tortuosity τ are used in the literature. Thus, the different tortuosity definitions will be presented prior to reviewing the literature concerned with determining the tortuosity or the effective ionic conductivity of porous battery separators and electrodes.

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Section: Theorymentioning

confidence: 99%

Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy

Landesfeind

Hattendorff

Ehrl

et al. 2016

J. Electrochem. Soc.

486

596

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“…The lower charge-transfer resistance of N1 relative to N2 verifies the presence of more sub-band-gap states between the conduction and valence bands and explains the higher capacity of N1 relative to N2 cathode material. Three main factors can affect the CPE impedance: (1) electrode surface roughness [37], (2) the distribution of reaction rate or current distribution [38] and (3) varying thickness and composition [39]. Surface roughness, defined as (D = (n ?…”

Section: Electrochemical Impedance Spectroscopymentioning

confidence: 99%

Synthesis, characterization and electrochemical performances of γ-Fe2O3 cathode material for Li-ion batteries

Abbasi

Mirhabibi

Arabi³

et al. 2016

J Mater Sci: Mater Electron

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Maghemite nanoparticles were successfully synthesized via a co-precipitation method and electrochemical-optical properties of three different sizes were studied. Using this material as a Li-ion battery cathode, the results of charge-discharge tests showed that decreasing the maghemite particle size increased the lithium hosting capacity. First discharge capacities for cathodes made of material of particle size 11 and 19 nm were 206 and 186 mAh g -1 respectively, while for micron-sized cathode material a discharge capacity of 26 mAh g -1 was obtained. Electrochemical impedance spectroscopy (EIS) was used to derive equivalent circuit elements, which confirmed a reduction in lithium insertion resistance for material with a smaller particle size. EIS investigations disclosed that the R ct and Z W reduced with reduction of particle size, which indicates cathode material with lower particle size is more suitable. Band-gaps of the materials were determined using the diffuse reflectance spectroscopy technique on the base of Kubelka-Munk theory. The results showed that the needed energy for electron conduction reduces with reduction of particle size, which results in capacity enhancement.

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“…12(a), known as a Randles circuit, was used to t the experimental impedance data of the Mo(Si 1Àx Al x ) 2 lms oxidized at 500 C for 10 h. In this circuit, a constant phase element (CPE) is introduced to obtain a best t, instead of an ideal capacitance element, due to the surface heterogeneity originating from surface roughness, porosity or inhomogeneous distribution of the electrode surface properties. 39,40 The impedance of CPE is normally expressed as:…”

Section: Characterization Of Oxide Scales By Impedance Spectroscopymentioning

confidence: 99%

Oxidation resistance of Mo(Si_1−xAl_x)₂ nanocrystalline films and characterization of their oxide scales by electrochemical impedance spectroscopy

Munroe

et al. 2014

RSC Adv.

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To explore the influence of Al alloying on the oxidation resistance of MoSi 2 , four Mo(Si 1Àx Al x ) 2 nanocrystalline films, with differing Al contents, were fabricated on Ti-6A1-4V substrates by a doublecathode glow discharge technique and their cyclic oxidation behavior was characterized at 500 C in air.The oxidation kinetics of the four Mo(Si 1Àx Al x ) 2 films was found to obey a subparabolic behavior with respect to the overall exposure, and their oxidation resistance was improved by Al additions. On the other hand, the electrochemical behavior of the oxide scales developed on the four Mo(Si 1Àx Al x ) 2 nanocrystalline films in a 3.5 wt% NaCl solution was studied using electrochemical-impedance spectroscopy (EIS). The impedance data showed that with increasing oxidation time, the oxide scales transformed from a homogeneous and dense structure to a duplex structure consisting of a porous outer layer and a denser inner layer. The resistance of the oxide scales increased with increasing Al addition, implying an enhanced protective ability of the oxide scales by Al alloying in media containing chlorine ions. The findings represent a step forward in improving the surface integrity of alloy components used in the hot zones of jet engines.

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An investigation of the capacitance dispersion on the fractal carbon electrode with edge and basal orientations

Cited by 187 publications

References 19 publications

Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy

Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy

Synthesis, characterization and electrochemical performances of γ-Fe2O3 cathode material for Li-ion batteries

Oxidation resistance of Mo(Si_1−xAl_x)₂ nanocrystalline films and characterization of their oxide scales by electrochemical impedance spectroscopy

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An investigation of the capacitance dispersion on the fractal carbon electrode with edge and basal orientations

Cited by 187 publications

References 19 publications

Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy

Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy

Synthesis, characterization and electrochemical performances of γ-Fe2O3 cathode material for Li-ion batteries

Oxidation resistance of Mo(Si1−xAlx)2 nanocrystalline films and characterization of their oxide scales by electrochemical impedance spectroscopy

Contact Info

Product

Resources

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Oxidation resistance of Mo(Si_1−xAl_x)₂ nanocrystalline films and characterization of their oxide scales by electrochemical impedance spectroscopy