Diffusion Impedance Research Articles

Large-field detection of Metal/CFRP hybrid composites based on air-coupled laser ultrasound

Metal/carbon fiber reinforced polymer (CFRP) hybrid composites are widely used in the aeronautical and aerospace industry due to their excellent mechanical properties. However, traditional nondestructive testing methods are difficult to achieve fast, non-contact, large-field, high resolution, and high contrast detection at the same time, due to the large differences in thickness, density, acoustic impedance, and thermal diffusion between metal and fiber layers. Here, an air-coupled laser ultrasound (ACLU) method was presented for large-field detection of internal defects on the non-homogeneous metal/CFRP interface. Simulation analysis was conducted to analyze the propagation characteristics of laser ultrasound in Al/CFRP hybrid composites without defect and with defect. Test results for ACLU system display that the maximum imaging field of view is 300 mm × 75 mm at the frame rate of 1.5 s/frame. Under a 0.3 mm metal layer, the detecting resolution of the system can still reach up to 200 μm. The system was applied to detect three types of crack and disbond defects of metal/CFRP hybrid composites, and making a side-by-side comparison with phased array ultrasonic testing (PAUT) and radiographic testing (RT). The C-scan results show that the constructed system obtains a high signal-to-noise ratio (SNR) of 23 dB, which improves 4 times and 20 times compared with PAUT and RT, respectively. It indicates that the developed ACLU system hold a great prospect in non-contact large-field inspection of metal/CFRP hybrid composites.

Preparation of amorphous TiO2 films by RF magnetron sputtering: Process optimization and effect of sputtering pressure on electrochromic properties

In this study, radio frequency (RF) magnetron sputtering was utilized to fabricate Titanium dioxide (TiO2) thin films at a room temperature. Scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, electrochemical workstation, and UV–Vis spectrophotometry were employed to analyze and characterize the microstructure, compositional components, and electrochromic properties of the films. The main focus is on exploring the microstructure and electrochromic properties of films produced under diverse sputtering pressures. The results show that the TiO2 films fabricated at a sputtering pressure of 1.2 Pa exhibit the most desirable surface morphology, with an optical modulation amplitude of up to 49.18 % (@550 nm), coloring time of 1.28 s, bleaching time of 0.79 s, and a coloration efficiency of 21.07 cm2/C. After 1000 cyclic voltammetry tests, the Q decay rate is 51.75 %. Electrochemical impedance spectroscopy (EIS) measurements reveal that TiO2 films prepared under these process parameters have lower charge transfer resistance and ion diffusion impedance, which facilitate ion injection and extraction.

Cross-Scale Decoupling Kinetic Processes in Lithium-Ion Batteries Using the Multi-Dimensional Distribution of Relaxation Time.

To non-destructively resolve and diagnose the degradation mechanisms of lithium-ion batteries (LIBs), it is necessary to cross-scale decouple complex kinetic processes through the distribution of relaxation times (DRT). However, LIBs with low interfacial impedance render DRT unreliable without data processing and closed-loop validation. This study proposes a hierarchical analytical framework to enhance timescale resolution and reduce uncertainty, including interfacial impedance reconstruction and multi-dimensional DRT analysis. Interfacial impedance is reconstructed by eliminating simulated inductive and diffusive impedance based on a high-fidelity frequency-domain model. Multi-dimensional DRT decouples solid electrolyte interphase (SEI) and charge transfer (CT) processes by the reversibility of electrochemical reactions with state of charge (SOC) to characterize electrode kinetic evolution driven by SOC and temperature through timescales and peak area. The findings reveal that reconstructed impedance improves the accuracy of identified time constants by ≈20%. Cross-scale DRT results reveal that SOCs below 10% at 25 °C effectively distinguish electrode kinetics due to the high correlation between cathodic CT and SOC. Kinetic metrics characterize that anodic SEI or CT are different control steps limiting the low-temperature performance of different cells. This work underscores the potential of the proposed framework for non-destructive diagnostics of kinetic evolution.

Deoxynivalenol exposure disturbs the cytoplasmic maturation in porcine oocytes

Deoxynivalenol (DON) is a secondary metabolite of Fusarium fungi and belonged to trichothecenes, and it widely presents in various food commodities. Previous studies have highlighted its potent toxicity, adversely affecting the growth, development, and reproductive in both humans and animals. However, the potential impact of DON on porcine oocyte organelles remains elusive. In present study, we delved into the toxic effects of DON on mitochondria, endoplasmic reticulum, Golgi during the porcine oocyte maturation. Our findings revealed that DON exposure significantly impeded granulosa cell diffusion and the expulsion of the first polar body. Additionally, mitochondrial fluorescence intensity and membrane potential underwent notable alterations under DON exposure. Notably, lysosomal fluorescence intensity decreased significantly, suggesting protein degradation and potential autophagy, which was further corroborated by the enhanced fluorescence intensity of LC3. Furthermore, endoplasmic reticulum fluorescence intensity declined, and DON exposure elevated endoplasmic reticulum stress levels, evident from the upregulated expression of GRP78. Concurrently, we observed disruption in the fusiform cortex distribution of the Golgi apparatus, characterized by reduced Golgi apparatus fluorescence intensity and GM130 expression. Collectively, our results indicate that DON exposure profoundly affects the fundamental functions of porcine oocyte organelles during meiosis and maturation.

Effect of Silk Fibroin on the Mechanical and Transport Properties of Agarose Hydrogels.

In this work, the effect of incorporating silk fibroin, a fibrous biocompatible protein, into physically cross-linked agarose hydrogels was investigated as a simple model study to examine how supramolecular fibrous structures influence the properties of the hydrogels. The rheological and transport properties were studied. Fibroin did not change the general viscoelastic properties of the investigated hydrogels but changed the viscoelastic moduli values and also the mesh size, as calculated from rheometry data. Fibroin influenced the mechanical properties depending on its concentration: at lower concentrations, it increased the mesh size, while at higher concentrations, it acted as a filler, decreasing the mesh size. Similarly, the storage and loss moduli were affected, either increasing or decreasing based on the fibroin concentration. The fibroin effect on the diffusion of two dyes differing in their charge was the result of a combination of structural effects, responsible also for changes in the rheological properties, and a result of electrostatic interactions between the charged groups. For positively charged methylene blue, low fibroin concentrations accelerated diffusion, while higher concentrations slowed it by filling network vacancies. In contrast, for negatively charged eosin-B, fibroin strongly impeded diffusion at all concentrations due to electrostatic repulsion, leading to its accumulation at the hydrogel interface. The findings of this work may contribute to an understanding of the behavior of the extracellular matrix or soft tissues as well as to the development of the tailored design of hydrogel materials.

Mechanistic Insights on Direct Ammonia Solid Fuel Cell Using Ni-YSZ Anode: Experimental and Density Functional Theory Studies

While Ni-Yttria-stabilized zirconia (Ni-YSZ) cermet exhibits a great potential to realize high-efficiency ammonia to power using direct ammonia solid oxide fuel cell (DA-SOFC), the mechanisms of NH3 cracking and H2 oxidation reactions as well as direct electro-oxidation of ammonia are still unclear. In this context, with the motivation, the DA-SOFC performance of fuel electrode (Ni-YSZ) using conventional anode-supported cell (Ni-YSZ|YSZ|GDC-LSCF) is studied through microscale observation coupled with density functional theory (DFT) calculations to unravel the reaction mechanisms on Ni-YSZ(111) anode. The performance of DA-SOFC is examined using NH3, H2 and N2/H2 mixture as fuel at the temperature range of 700-800℃. In addition to XRD and SEM-EDX characterizations, the electrochemical characterization is performed using the impedance spectroscopy (EIS) measurements at three different temperatures of 700, 750 and 800 °C. Interestingly, the experimentally observed trend in Open-circuit voltage (OCV) implies that direct electro-oxidation of ammonia is the dominant reaction mechanism. Notably, polarization resistance is primarily contributed by ammonia anodic reaction and secondarily by the gas diffusion impedance. DFT results revealed that ammonia adsorbs favorably on the Ni cluster, and hydrogen follows a dissociative mode of adsorption on the Ni cluster. The activation barriers of elementary steps involved in the proposed mechanisms for fuel cracking and oxidation reactions are computed. This work is anticipated to provide valuable insights into the rational design of Ni-YSZ-based fuel electrodes. Keywords: ammonia, hydrogen, SOFC, fuel cells, DFT, reaction mechanism

Femtosecond laser ablated trench array for improving performance of commercial solid oxide cell

The performance of electrode-supported solid oxide cells (SOCs) is limited adversely by gas diffusion impedance in thick and porous support. This work focuses on the improvement of gas transport properties of commercial Ni-YSZ anode-supported SOFC by femtosecond laser-based micromachining where micro-holes of identical depth but different hole separations pitches with minimal heated affected zones were imposed. The polarization resistance calculations and DRT analysis revealed that the presence of the micro-holes improves fuel transport in the anode active zone of commercial SOFC. The presence of the micro-holes resulted in up to 20.8 % and up to 17.2 % reduction in polarization resistance for dry H2 and wet H2 gas-fueled SOFC samples, respectively. Moreover, the decrease in intensity of peaks responsible for fuel diffusion with increasing micro-holed density was observed. Therefore, dense and sparse cells exhibited a performance augmentation of 25 % and 11 % in dry H2 and enhancement of 16 % and 15.6 % in wet H2, respectively. Fs-laser ablation appeared as a unique capability for the post-processing of SOFC elements via imposing different gas channel geometries.

Low-frequency approximations to the finite-length Warburg diffusion impedance: The reflexive case

A study on the influence of the characteristic parameters of the finite-length diffusion processes on the galvanostatic dynamic response of electrochemical systems described by the reflexive Warburg impedance, is presented. The characteristic frequencies of the reflexive diffusion impedance, originally including those of the purely diffusive behaviour, are identified. The galvanostatic charge/discharge cycle is interpreted from the truncated series obtained from the development into partial fractions of the impedance. The low-frequency behaviour is also compared to the impedance obtained from the development into continued fractions with an only characteristic frequency. Interesting results associated to the transition between the capacitive and diffusive behaviours, emerge from the use of a hybrid methodology dealing with frequency and time domains. A simple electric circuit physically based on the series developments of the reflexive Warburg impedance with an only relaxation time, is used to interpret the galvanostatic charge curve of a commercial supercapacitor and to validate the theoretical study.

Self-Assembled Nanocomposite Based on SrCo0.7Fe0.2Sc0.1O3-δ as an Efficient Intermediate-to-Low-Temperature SOFC Cathode.

The high performance of intermediate-to-low temperature solid oxide fuel cells (ILT-SOFCs) closely depends on the catalytic activity of the cathode material. However, most high-activity perovskite cathodes are rich in Sr and will arise from Sr segregation during the long-term working, resulting in the decay of activity and stability. Herein, by regulating the calcined way and temperature, a type of self-assembled nanocomposite perovskite cathode is developed, the stoichiometric SrCo0.7Fe0.2Sc0.1O3-δ (SCFSc) powder self-separates into a cubic phase (Pm3̅m, Sc-rich) and a tetragonal phase (P4/mmm, Sc-fewer). Meanwhile, a single cubic phase is prepared with the same formula via calcining the SCFSc pellet. It is found that the nanocomposite cathode shows better oxygen reduction reaction catalytic activity than single cubic SCFSc, caused by lower impedance of oxygen surface exchange and bulk diffusion. Particularly, the nanocomposite SCFSc cathode with the self-assembled heterointerfaces mitigates the Sr segregation and shows a peak power density of 1.17 W cm-2 at 700 °C and excellent stability for ∼101 h at 600 °C. This work provides a strategy for the development of nanocomposite cathodes to mitigate cation segregation and improve catalytic activity and stability.

Er3+/ Yb3+ co-doped multi-functional silica phosphate glass films for integrated photonic applications

The multi-component silicate glasses co-doped with Er3+/Yb3+ were fabricated as thin films by the spin coating technique, which was analyzed for their optoelectronic response. Their monolith counterparts synthesized by the sol-gel route were used for the electrical studies. The films evidenced nanocristobalite phases at low levels of doping. The film micrographs explicated gas-trapped circular dimensions on the surface, due to the spreading of the sol on the substrate during the spin coating process. The glasses show a decrease in the number of polarizable non-bridging oxygen units with doping, reducing the polarizability and optical basicity. The films exhibit prominent green lasing in the downshifting process. The energy transfer from the Yb3+ ions endows the glasses with significant red lasing, suppressing the green emissions by the upconversion mechanism, which is also validated by the colorimetric chromaticity analysis. The gain cross-section of the glass doped with 1.5 mol% of Yb3+ is 23.3 × 10−20 cm2 in the S-band telecommunication domain. The glass film evidences its potential for NIR lasers, beyond a population inversion of 40 %, and a decreasing metastable lifetime of 6.6 μs. Beyond 1.5 mol% of the co-dopant Yb3+, energy transfer dominates, due to the dipole-quadrupole interactions, which has been corroborated by the Inokuti-Hirayama model. The conductivity in the glasses shows a decreasing trend with doping. The Randle's equivalent circuitry of the Nyquist impedance plots, predicts Warburg diffusion impedance that deters the space charge polarization. The consequential decrease in the dielectric constant and capacitance makes the glasses suggestive of multi-layer dielectric substrates in the integrated microelectronic technology for soldering of the printed circuit boards (PCB) that demand low signal losses.

Electrospun Co-Ni mixed multiple oxidation states heterostructure for high-performance Li-ion battery

With the increasing prevalence of mobile electronic devices, electric vehicles, and other technological advancements, there is a growing demand for higher-capacity Lithium-ion batteries (LIBs). Metal-organic frameworks (MOFs) have been actively researched in recent years due to their numerous advantages. However, the irreversible collapse during lithium-ion interaction hampers MOFs’ electrochemical stability. This study employs a direct precipitation method to synthesize uniformly shaped MOF materials, followed by carbon coating using electrospinning techniques, and ultimately, derivatives of MOF materials are produced through annealing. Thanks to this innovative material design process, exceptional performance is observed in this material as a lithium-negative electrode. After 1000 cycles at a high current density of 1 A g−1, its reversible capacity stabilizes at 1318 mAh g−1. Moreover, this negative electrode material exhibits exceptional rate performance at various current densities. The Co3O4/NiO@NCNFs electrode demonstrates enhanced charge storage capacity due to the synergistic effects of diffusion and capacitance control processes. Additionally, this material exhibits characteristics of low impedance and high lithium-ion diffusion rate. This study presents a novel method for manufacturing lithium-ion battery negative electrode materials by integrating MOF materials with electrospinning technology.

Novel NASICON-type Mn0.5Ti2(PO4)3@F-doped carbon composite with high electrochemical performance as anode materials for potassium-ion batteries

Mn0.5Ti2(PO4)3 with a NASICON structural is used as an anode material in potassium-ion batteries due to its abundance of vacancies that can hold potassium ions. This characteristic not only contributes to its excellent stability but also results in a high specific capacity. However, the poor electrical conductivity of the polyanionic type structure limits the material's ability to fully utilize its capacity. In this paper, the conductivity and electrochemical stability of the Mn0.5Ti2(PO4)3 anode material are enhanced through composite formation with an F-doped carbon layer. The introduction of F into the carbon matrix creates a large number of vacancy defects and F active sites. The vacancies enhance the transport of potassium ions on the Mn0.5Ti2(PO4)3 material's surface, while the active sites exhibit strong electronegativity, improving the absorption of potassium ions. Therefore, the diffusion impedance of potassium ions is significantly reduced, leading to an increased diffusion rate of potassium ions. Attributing to the improved reaction kinetics, the Mn0.5Ti2(PO4)3@F-doped carbon composite demonstrates a high specific capacity of 86 mA h g−1 at 10,000 mA g−1 when used as the anode for potassium-ion batteries. Even more, the specific capacity remains a capacity of 136 mA g−1 after 3000 cycles at 1000 mA h g−1. This study enhances our comprehension of material design by investigating the alteration of carbon matrix to promote the electrochemical characteristics of materials.

Study of Solid-State Diffusion Impedance in Li-Ion Batteries Using Parallel-Diffusion Warburg Model

Anomalous diffusion impedance due to the solid-state Li+ diffusion in Li-ion batteries is often troublesome for the analysis. In this work, we propose a novel analytical Parallel-diffusion Warburg (PDW) model and couple it with the conventional equivalent electrical circuit model (EECM) analysis to tackle this long-standing challenge. The analytical expression of the PDW is derived from the classical Fickian diffusion framework, introducing non-unified diffusion coefficients that originate from the diverse crystalline conditions of Li+ diffusion paths, as theoretically demonstrated in the atomistic modeling results. The proposed approach (EECM + PDW) is successfully employed to study the diffusion impedance of thin-film LiNi0.5Mn1.5O4 (LNMO) electrodes and porous LiNi0.80Co0.15Al0.05O2 (NCA) electrodes, demonstrating the applicability and robustness of this method.

The Influence of Ink Chemistry on the Microstructure Evolution and GHz RF Response of Printed Ag Transmission Lines.

High-frequency transmission is limited to the skin depth in metals. Because poor conductivity cannot be compensated for by increasing the conductor thickness as with DC, optimal transport properties are prerequisites for radio frequency (RF) use. Structural and chemical analyses of transmission lines printed using a traditional ink consisting of Ag nanoflakes in a dispersing phase revealed that optimized thermal treatments yielded thorough burnout of the binder, significant grain growth, elimination of the pore volume, and electrical responses that were comparable to values obtained for thermally evaporated, fully dense Ag controls. Specifically, a low DC resistivity of 2.3 μΩ·cm (1.4× bulk Ag) and RF transmission coefficients of 0.87 and 0.75 at 5 GHz and 10 GHz, respectively, were measured in the nanoflake Ag prints. Conversely, in transmission lines printed from a metal-organic decomposition ink, residual chemical contamination impeded diffusion and densification, yielding greater porosity, small grains that are pinned, and a degraded RF response. Reasonably good porosity approximations were obtained from a model based on percolation theory. The results indicate that contaminants at interfaces and pore surfaces impede diffusion, pore elimination, and full densification, and further, alter carrier dynamics and degrade RF response.

On the Proper Use of a Warburg Impedance

Recent battery papers commonly employ interpretation models for which diffusion impedances are in series with interfacial impedance. The models are fundamentally flawed because the diffusion impedance is inherently part of the interfacial impedance. A derivation for faradaic impedance is presented which shows how the charge-transfer resistance and diffusion resistance are functions of the concentration of reacting species at the electrode surface, and the resulting impedance model incorporates diffusion impedances as part of the interfacial impedance. Conditions are identified under which the two model formulations yield the same results. These conditions do not apply for batteries.

Extending the calendar life of LiNi0.8Co0.1Mn0.1O2-based lithium-ion batteries via low-temperature storage

Given the widespread application of lithium-ion batteries (LiBs), additional in-depth aging investigations based on commercial batteries are necessary for safety and economic considerations. However, calendar aging, the loss of capacity caused by cell storage, is always neglected. Herein, the calendar aging patterns of LiNi0.8Co0.1Mn0.1O2 (NCM811)-based full and half cells are discussed. According to the electrochemical tests, the cell capacity decay increases with the storage state of charge (SOC), and storage time, and excellent capacity retention is demonstrated in low-temperature (LT) storage. Furthermore, in situ electrochemical impedance spectroscopy (EIS) reveals that the interfacial impedance of batteries increases significantly at LT and decreases rapidly upon return to room temperature (RT). It is hypothesized that the calendar aging is mainly controlled by the kinetic lithium diffusion impedance and the temperature-determined reaction rate. Finally, no adverse effects are found after LT storage, as revealed by the long-term cycling and electrode characterization results. It is recommended that long-term resting-state batteries should be stored at a suitable LT to prolong the calendar life.

Detecting microvascular invasion in hepatocellular carcinoma using the impeded diffusion fraction technique to sense macromolecular coordinated water.

Impeded diffusion fraction (IDF) is a novel and promising diffusion-weighted imaging (DWI) technique that allows for the detection of various diffusion compartments, including macromolecular coordinated water, free diffusion, perfusion, and cellular free water. This study aims to investigate the clinical potential of IDF-DWI in detecting microvascular invasion (MVI) in hepatocellular carcinoma (HCC). 66 patients were prospectively included. Metrics derived from IDF-DWI and the apparent diffusion coefficient (ADC) were calculated. Multivariate logistic regression was employed to identify clinical risk factors. Diagnostic performance was evaluated using the area under the receiver operating characteristics curve (AUC-ROC), the area under the precision-recall curve (AUC-PR), and the calibration error (cal-error). Additionally, a power analysis was conducted to determine the required sample size. The results suggested a significantly higher fraction of impeded diffusion (FID) originating from IDF-DWI in MVI-positive HCCs (p < 0.001). Moreover, the ADC was found to be significantly lower in MVI-positive HCCs (p = 0.019). Independent risk factors of MVI included larger tumor size and elevated alpha-fetoprotein (AFP) levels. The nomogram model incorporating ADC, FID, tumor size, and AFP level yielded the highest diagnostic accuracy for MVI (AUC-PR = 0.804, AUC-ROC = 0.783, cal-error = 0.044), followed by FID (AUC-PR = 0.693, AUC-ROC = 0.760, cal-error = 0.060) and ADC (AUC-PR = 0.570, AUC-ROC = 0.651, cal-error = 0.164). IDF-DWI shows great potential in noninvasively, accurately, and preoperatively detecting MVI in HCC and may offer clinical benefits for prognostic prediction and determination of treatment strategy.

FT-Raman spectroscopic and electrical investigations of RE3+ doped multi-functional silicate glasses for cathode plating and integrated microelectronic technology

Lanthanide-doped silicate glasses were subjected to structural and temperature-dependent electrical investigations to validate their multi-functionality in the integrated microelectronic industries. Raman-active vibrations around 920 cm−1 and 1330 cm−1 confirmed the silicate and phosphate tetrahedra respectively. The Er3+ doped glass demonstrated the highest dielectric constant of 9.21 × 105, while Sm3+ infused glass exhibited the lowest dielectric constant of 4.37 × 104 at 0.1 Hz and 473 K. The Sm3+ doped glasses are prospective for plating on copper chips in printed circuit boards that necessitate low dielectric constants to minimize propagation delay. The equivalent circuitry fitted for the Nyquist impedance plot of Er3+ doped glass constituted parallel combinations of a resistor and Constant Phase Element (CPE), in series with Warburg diffusion impedance. The CPE approaching a capacitive nature in the Er3+ doped glass could be suggested for cathode plating in batteries, and fabrication of multi-layer dielectric substrates in radio frequency condensers.

Corrosion behavior of Cr coating on ferritic/martensitic steels in liquid lead-bismuth eutectic at 600 °C and 700 °C

The surface coating technology, encompassing ceramics, refractory materials, metallic alloys containing Al or Si, and multicomponent composites, presents a viable approach to improve the corrosion resistance of ferritic/martensitic (F/M) steels with (9–12) wt.% Cr in liquid lead-bismuth eutectic (LBE) environment. Among these coating materials, chromium (Cr) coating emerges as a particularly noteworthy option. This study specifically focused on depositing a 3 μm thick Cr coating on on T91 and SIMP steels using magnetron sputtering. Subsequently, the corrosion behavior of the Cr coating was investigated in LBE at temperatures of 600 °C and 700 °C. The results revealed that, after 300 h at 600 °C, T91 and SIMP steels formed oxide scales with approximately 32.6 μm and 19.3 μm thicknesses, respectively. At 700 °C for 140 h, these oxide scales increased to about 82.4 μm and 73.1 μm for T91 and SIMP steels, respectively. However, the application of a Cr coating resulted in the formation of a dense layer of chromium oxide with a thickness of 4–5 μm. This layer effectively impeded oxygen diffusion and Fe migration leading to a significant reduction in the corrosion rate of the steel. Notably, the Cr coating maintained secure attachment to the steel even after exposure to high-temperature LBE corrosion. These findings underscore the capacity of coating to markedly enhance the corrosion resistance of T91 and SIMP steels in high-temperature LBE environments, providing robust protection against the detrimental effects of challenging conditions. Consequently, Cr coating emerges as a promising solution for future fission nuclear reactors.

Automatic Initialization and Model Selection for Li-ion Battery Impedance Identification in the Frequency Domain

Electrochemical Impedance Spectroscopy (EIS) is a useful tool for selecting a pertinent Equivalent Circuit Model (ECM) of a Li-ion battery. Impedance model is designed to describe low, middle and high frequency electrochemical processes involved. When considering low frequency restricted in the Warburg zone, diffusion impedance is modeled thanks to a Constant Phase Element (CPE) which behaves as a fractional integrator of order n close to 0.5. Phenomena observed in middle frequency are described using specific circuits called Zarc which consist in connecting a CPE in parallel with a resistor. Therefore, the global impedance model is characterized by non integer order operators and parameters can be estimated by a Complex Non linear Least Squares (CNLS) algorithm which requires a proper initialization in order to guarantee the convergence to a global optimum. The paper presents a method to analyze EIS data measurements in order to select automatically the number of middle frequency Zarc circuits required (one or two) and to initialize properly the CNLS algorithm. The method is validated using experimental open source EIS data.