Observation of long ionizing tracks with the ICARUS T600 first half-module

F. Arneodo, B. Bade"ek, A. Badertscher, B. Baiboussinov, M. Baldo Ceolin, G. Battistoni, B. Bekman, P. Benetti, E. Bernardini, M. Bischofberger, A. Borio di Tigliole, R. Brunetti, A. Bueno, E. Calligarich, M. Campanelli, C. Carpanese, D. Cavalli, F. Cavanna, P. Cennini, S. Centro, A. Cesana, C. Chen, D. Chen, D.B. Chen, Y. Chen, D. Cline, Z. Dai, C. De Vecchi, A. Dabrowska, R. Dolfini*, M. Felcini, A. Ferrari, F. Ferri, Y. Ge, A. Gigli Berzolari, I. Gil-Botella, K. Graczyk, L. Grandi, K. He, J. Holeczek, X. Huang, C. Juszczak, D. Kie"czewska, J. Kisiel, T. Koz"owski, H. Kuna-Ciska", M. Laffranchi, J. Łagoda, Z. Li, F. Lu, J. Ma, M. Markiewicz, A. Martinez de la Ossa, C. Matthey, F. Mauri, D. Mazza, G. Meng, M. Messina, C. Montanari, S. Muraro, S. Navas-Concha, M. Nicoletto, G. Nurzia, S. Otwinowski, Q. Ouyang, O. Palamara, D. Pascoli, L. Periale, G. Piano Mortari, A. Piazzoli, P. Picchi, F. Pietropaolo, W. P ! o"ch"opek, T. Rancati, A. Rappoldi, G.L. Raselli, J. Rico, E. Rondio, M. Rossella, A. Rubbia, C. Rubbia, P. Sala, D. Scannicchio, E. Segreto, F. Sergiampietri, J. Sobczyk, J. Stepaniak, M. Szeptycka, M. Szleper, M. Szarska, M. Terrani, S. Ventura, C. Vignoli, H. Wang, M. W ! ojcik, J. Woo, G. Xu, Z. Xu, A. Zalewska, J. Zalipska, C. Zhang, Q. Zhang, S. Zhen, W. Zipper a INFN Laboratori Nazionali del Gran Sasso, s.s. 17bis Km 18+910, Assergi (L'Aquila), Italy b Institute of Experimental Physics, Warsaw University, Warszawa, Poland c Institute for Particle Physics, ETH H . onggerberg, Z . urich, Switzerland Dipartimento di Fisica e INFN, Universit " a di Padova, via Marzolo 8, Padova, Italy Dipartimento di Fisica e INFN, Universit " a di Milano, via Celoria 16, Milano, Italy f Institute of Physics, University of Silesia, Katowice, Poland Dipartimento di Fisica e INFN, Universit " a di Pavia, via Bassi 6, Pavia, Italy Dpto de F!isica Te ! orica y del Cosmos & C.A.F.P.E., Universidad de Granada, Avda. Severo Ochoa s/n, Granada, Spain Dipartimento di Fisica e INFN, Universit " a dell'Aquila, via Vetoio, L'Aquila, Italy CERN, CH-1211 Geneva 23, Switzerland Politecnico di Milano (CESNEF), Universit " a di Milano, via Ponzio 34/3, Milano, Ital

Inductance correction in impedance study of solid oxide fuel cells

A procedure for evaluation and elimination of errors, caused by parasitic inductance and resistance in EIS studies of two solid oxide fuel cells (SOFC) materials: yttria stabilized zirconia (YSZ) electrolyte and lanthanum strontium manganite (LSM)/YSZ composite cathode is presented in this paper. It is shown that for these low impedance systems the parasitic inductance can affect not only the high frequencies but also the middle and low ones. The parasitic errors correction procedure increases significantly the reliability of the electrochemical impedance spectroscopy (EIS) results

Electrochemical performance of Ni-based anodes for solid oxide fuel cells

The catalytic activity of Ni-based anodic materials was investigated in complete solid oxide fuel cells (SOFCs) by electrochemical analysis. Button cells, consisting of supporting yttria-stabilized zirconia (YSZ) electrolyte layer, (La1-xSrx)y MnO3 (LSM) cathode and (cermet) Ni0.5Co0.5\u2013YSZ anode were employed. Powders for anodes were obtained by wet impregnation. This pro- cedure allowed easy production of composite electrodes with homogeneous distribution of phases and controlled microstructure. Two electrodes impedance spectroscopy was carried out at different temperatures and partial pres- sures of reacting gases in order to evaluate contribution of each component to overall cell losses. Current\u2013voltage characteristic curves were also collected. Feeding with CH4 was tested and compared to H2. No deterioration of cell performance due to carbon formation at anode was observed over a test period of 100 h

Morphology and electrochemical activity of SOFC composite cathodes: I. experimental analysis

This paper describes the first part of an experimental and theoretical study performed on composite Lanthanum Strontium Manganite (LSM) and Yttria-stabilized Zirconia (YSZ) electrodes. Cathode electrocatalytic activity was investigated using different cell configurations and carrying out potentiodynamic polarisation and electrochemical impedance spectroscopy measurements (EIS). Measurements were carried out at different oxygen partial pressures, overpotentials, temperatures and electrode geometries. In order to identify the main steps involved in cathodic oxygen reduction, the NLLS-Fit procedure was used. The results for different cell geometries agree with each other, suggesting a transition in the overall reaction mechanism, from charge transfer to mass transfer control, at a critical temperature of about 750 A degrees C. The experimental results also show a remarkable effect of electrode thickness on the overall reaction rate, throughout the temperature range tested. A grey level gradient along the thickness of the thicker electrodes were detected by analyzing microscopic images of the cells. These results, together with electrochemical measurements on cathodes with different thickness, confirm that morphology plays a key role in determining the performance of Solid Oxide Fuel Cells (SOFC) composite cathodes

Impedance Simulations of SOFC LSM/YSZ Cathodes with Distributed Porosity

The cathode represents the main source of energy loss in hydrogen fed solid oxide fuel cells (SOFCs). In order to reduce the polarization resistance, porous composite cathodes, which consist of sintered random structures of electron-conducting (e.g., strontium-doped lanthanum manganite, LSM) and ion-conducting (e.g., yttria-stabilized zirconia, YSZ) particles, are often used. The optimization of the electrode performance requires the understanding of all the phenomena involved (e.g., electrochemical reaction, charge and gas phase mass transport) and their dependence on the geometric and microstructural electrode features. Both mathematical models and electrochemical impedance spectroscopy (EIS) measurements are usually used to get this goal. In this study, a mechanistic model for the simulation of EIS in composite LSM/YSZ cathodes is presented. The model is based on mass and charge balances in transient conditions and accounts for the variation of porosity along the electrode thickness as experimentally observed on scanning electron microscope images. The continuum approach is used, which describes the composite structure as a continuum phase characterized by effective properties, related to morphology and material properties by percolation theory. Simulated results are compared with experimental spectra for different electrode thicknesses (5-85\u3bcm) and temperatures (650-850\ub0C). The comparison allows the evaluation of a macroscopic capacitance of the double layer at each interface LSM-YSZ, which is constant with electrode thickness. It is found that the low frequency arc (from 3.5 to 250Hz for temperatures respectively from 650\ub0C to 850\ub0C) is due to the double layer capacitance. However, there is not a clear relationship between the latter and the temperature, suggesting that the macroscopic capacitance gathers in itself several phenomena which have different behaviors with temperature

The design optimization of nanostructured hierarchical electrodes for solid oxide cells by artificial impregnation

Microstructural correlations of impregnated freeze tape cast scaffolds for solid oxide cells are studied by coupling experimental and modelling approaches. The functional and supporting layers of the hierarchical porous backbones are initially reconstructed by synchrotron X-ray micro- and nano-holotomography, respectively. A particle-based model was then built to numerically infiltrate the scaffold walls with hemispherical nanoparticles. The electrode microstructural properties are evaluated on the artificially impregnated electrodes as function of the catalyst loading. A parametric investigation on the effect of the nanoparticle size is performed to analyse the evolution of the electrode characteristics. It has been shown that the volume fraction of the infiltrated phase necessary to reach the percolating threshold is increased while increasing the nanoparticle size. The density of active sites presents a maximum as function of the catalyst loading that depends on the particle size. The volume fraction of infiltrated phase required to reach the percolating threshold in the diffusion layer is one order of magnitude lower than in the functional layer (∼1 vol% compared to 3–8 vol%, respectively). The analyses contained in this paper aim at guiding the manufacturing process to the shaping of innovative electrodes microstructures combining both high activation and mass transfer properties

Study of reversible SOFC/SOEC based on a mixed anionic-protonic conductor

This paper deals with the fabrication and electrochemical study of a high temperature solid electrolyte supporting cell operating as SOFC (Solid Oxide Fuel Cell) and SOEC (Solid Oxide Electrolysis Cell). The cell is based on a dual membrane (DM) electrolyte design, advantageously separating the cell into three different chambers: hydrogen side, oxygen side, and dual membrane (DM), where H2O production or splitting takes place in SOFC or SOEC mode respectively. The supporting electrolyte consists of a dense/porous/dense tri-layer, exclusively made of BaCe0.85Y0.15O3 12\u3b4 (monolithic design), which is a mixed anionic-protonic conductor. The assembly was fabricated by tape casting, adding pore formers to control porosity. The cell was then electrochemically studied under different operating conditions of temperature, overpotentials and gas feeding, either in SOFC and SOEC mode. From the results presented here, it can be observed that, in spite of dense and thick electrolyte layers and platinum electrodes, the electrochemical study of the cell showed: (i) promising power density, (ii) interesting SOFC/SOEC operating mode reversibility, (iii) proved H2O production in the porous dual membrane when the cell operates as a fuel cell, and proved splitting of the H2O molecules contained in the porous dual membrane when the cell operates as an electrolyser. Investigations of cell performance degradation were also conducted

Understanding the electrochemical behaviour of LSM-based SOFC cathodes. Part II - Mechanistic modelling and physically-based interpretation

This study presents a physically-based model for the impedance simulation of the oxygen reduction reaction in porous strontium-doped lanthanum manganite (LSM) cathodes. The model describes the surface mechanism only, taking into account the co-limited adsorption/diffusion of oxygen and the charge-transfer reaction at the three-phase boundary (TPB). After calibration with experimental impedance spectra, themodel is used to identify the transition of kinetic regime fromthe surface to the bulk pathmechanism,which occurs at cathodic dc bias of ca. 0.2 V within 700\u2013800 \ub0C. The transition is highlighted by a significant decrease in impedance and the appearance of a low-frequency inductive loop. The model consistently reproduces the impedance spectra before the transition of kinetic regime with a single set of parameters, allowing for the deconvolution of two features, one associated with the co-limited adsorption/diffusion process (ca. 5 Hz) and another minor contribution due to the charge-transfer at the TPB (ca. 35 Hz). The model and its parameters, which quantitatively agree with the literature, can be used as a basis to optimize the microstructural and surface properties of technical LSMbased cathodes, showing that the TPB length is not the main parameter to be maximized