A formalism to compare electrocatalysts for the oxygen reduction reaction by cyclic voltammetry with the thin-film rotating ring-disk electrode measurements

This report describes a general method to correlate the features determining the performance of an electrocatalyst (EC), including the accessibility of O2 to the active sites and the kinetic activation barrier, with the outcome of conventional electrochemical experiments. The method has been implemented for oxygen reduction reaction ECs by cyclic voltammetry with the thin-film rotating ring-disk electrode setup. The method (i) does not rely on the simplifications associated with the Butler-Volmer kinetic description of electrochemical processes and (ii) does not make assumptions on the specific features of the EC, allowing to compare accurately the kinetic performance of oxygen reduction reaction ECs with completely different chemistry. Finally, with respect to other widespread figures of merit (e.g. the half-wave potential E1/2), the figure of merit here proposed, for example, E(jPt[5%]), allows for much more accurate comparisons of the kinetic performance of ECs

METHOD AND PLANT FOR ACTIVATING CATALYSTS

La presente invenzione si riferisce ad un metodo di attivazione di un materiale catalizzatore solido, ad un catalizzatore attivato ottenibile da detto metodo di attivazione, ad una cella a combustibile, un elettrolizzatore, una batteria metallo-aria o una marmitta catalitica contenente detto catalizzatore attivato, nonché ad un impianto per realizzare detto metodo di attivazione

Interplay between Conductivity, Matrix Relaxations and Composition of Ca-Polyoxyethylene Polymer Electrolytes

This article also appears in: In Memoriam: Prof. Jean-Michel Savéant.In this report, the conductivity mechanism of Ca2+-ion in polyoxyethylene (POE) solid polymer electrolytes (SPEs) for calcium secondary batteries is investigated by broadband electrical spectroscopy studies. SPEs are obtained by dissolving into the POE hosting matrix three different calcium salts: CaTf2, Ca(TFSI)2 and CaI2. The investigation of the electric response of the synthetized SPEs reveals the presence in materials of two polarization phenomena and two dielectric relaxation events. It is demonstrated that the nature of the anion (i. e., steric hindrance, charge density and ability to act as coordination ligand) and the density of “dynamic crosslinks” of SPEs is fundamental in the establishment of ion-ion/ion-polymer interactions. The long-range charge migration processes occurring along the two revealed percolation pathways of the electrolytes are generally coupled with the polymer host dynamics and depend on the temperature and the anion nature. This study offers the needed tools for understanding Ca2+ conduction in POE-based electrolytes.This work has been supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 829145(FETOPEN-VIDICAT).V. Di Notothanks the University CarlosIII of Madrid for the “Catedras de Excelencia UC3M-Santander” (Chairof Excellence UC3M-Santander)

A New Glass-Forming Electrolyte Based on Lithium Glycerolate

The detailed study of the interplay between the physicochemical properties and the long-range charge migration mechanism of polymer electrolytes able to carry lithium ions is crucial in the development of next-generation lithium batteries. Glycerol exhibits a number of features (e.g., glass-forming behavior, low glass transition temperature, high flexibility of the backbone, and efficient coordination of lithium ions) that make it an appealing ion-conducting medium and a challenging building block in the preparation of new inorganic–organic polymer electrolytes. This work reports the preparation and the extensive investigation of a family of 11 electrolytes based on lithium glycerolate. The electrolytes have the formula C3H5(OH)3−x(OLi)x, where 0 ≤ x ≤ 1. The elemental composition is evaluated by inductively coupled plasma atomic emission spectroscopy. The structure and interactions are studied by vibrational spectroscopies (FT-IR and micro-Raman). The thermal properties are gauged by modulated differential scanning calorimetry and thermogravimetric analysis. Finally, insights on the long-range charge migration mechanism and glycerol relaxation events are investigated via broadband electrical spectroscopy. Results show that in these electrolytes, glycerolate acts as a large and flexible macro-anion, bestowing to the material single-ion conductivity (1.99 × 10−4 at 30 °C and 1.55 × 10−2 S∙cm−1 at 150 °C for x = 0.250)

Poly(vinyl alcohol)-based Electrolyte for Lithium Batteries

Polymer electrolytes (PEs) were first proposed in the early 1970s [1]. Since then, this class of materials has attracted the attention of many scientists, becoming one of the most prolific research field in solid-state electrochemistry [2, 3]. PEs, when used in Li-ion secondary batteries, are able to overcome many of the disadvantages of classic liquid organic electrolytes, which typically show: a) a high flammability and a high vapor pressure; b) a low thermal, chemical, and electrochemical stability; and c) dendrites formation. Nevertheless, classical PEs show low values of ionic conductivity (\u3c3 < 10-6 S cm-1) with respect to the typically requested conductivity values for practical applications. It has been shown that systems based on poly(vinyl alcohol) (PVA) are able to dissolve lithium salts, giving rise to ion conducting materials that present higher conductivity values with respect to any other solid and solvent-free polymer electrolyte [4]. Nonetheless, in classic PEs, the ionic conductivity is mainly attributed to the migration of anionic species. Indeed, in these materials the Li+ transference number is usally very low (< 0.3) [5]. Here, we present a new ion conducting polymer electrolyte based on a Li+ poly(vinyl alkoxide) macromolecular salt. In this material, Li+ ions are provided by PVA alkoxide groups (-RO-Li+) which are obtained by a direct lithiation of hydroxyl groups of pristine polymer. Thus, a PE is obtained with Li+ cations coordinated by the O- ligand functionalities directly bonded to the PVA backbone chains. The lithium assay is determined by Inductively-Coupled Plasma Atomic Emission Spectroscopy. The thermal stability is gauged using High-Resolution Thermo Gravimetric Analysis and the thermal transitions are investigated by means of Modulated Differential Scanning Calorimetry measurements. The structure and the interactions in proposed electrolytes are studied by vibrational spectroscopies both in the mid- and far-infrared and Raman spectroscopy. The interplay between structure and conductivity is investigated by Broadband Electrical Spectroscopy. Insights on the long range charge migration phenomena in these materials are presented. Acknowledgements: The authors thank the strategic project MAESTRA of the University of Padova for funding these research activities and the \u201cCentro studi di economia e tecnica dell\u2019energia Giorgio Levi Cases\u201d for PhD grant to G.P. References [1] D.E. Fenton, J.M. Parker, P.V. Wright, Polymer, 14 (1973) 589-. [2] V. Di Noto, S. Lavina, G.A. Giffin, E. Negro, B. Scrosati, Electrochim. Acta, 57 (2011) 4-13. [3] J. Muldoon, C.B. Bucur, N. Boaretto, T. Gregory, V. Di Noto, Polymer Reviews, 55 (2015) 208-246. [4] M. Forsyth, H.A. Every, F. Zhou, D.R. MacFarlane, Ionic Conductivity in Glassy PVOH-Lithium Salt Systems, ACS Symp. Ser., 1998, pp. 367-382. [5] F. Bertasi, K. Vezz\uf9, E. Negro, S. Greenbaum, V. Di Noto, Int. J. Hydrogen Energy, 39 (2014) 2872-2883

A New Glass-Forming Electrolyte Based on Lithium Glycerolate

he detailed study of the interplay between the physicochemical properties and the long-range charge migration mechanism of polymer electrolytes able to carry lithium ions is crucial in the development of next-generation lithium batteries. Glycerol exhibits a number of features (e.g., glass-forming behavior, low glass transition temperature, high flexibility of the backbone, and efficient coordination of lithium ions) that make it an appealing ion-conducting medium and a challenging building block in the preparation of new inorganic-organic polymer electrolytes. This work reports the preparation and the extensive investigation of a family of 11 electrolytes based on lithium glycerolate. The electrolytes have the formula C3H5(OH)(3)(-x)(OLi)(x), where 0 <= x <= 1. The elemental composition is evaluated by inductively coupled plasma atomic emission spectroscopy. The structure and interactions are studied by vibrational spectroscopies (FT-IR and micro-Raman). The thermal properties are gauged by modulated differential scanning calorimetry and thermogravimetric analysis. Finally, insights on the long-range charge migration mechanism and glycerol relaxation events are investigated via broadband electrical spectroscopy. Results show that in these electrolytes, glycerolate acts as a large and flexible macro-anion, bestowing to the material single-ion conductivity (1.99 x 10(-4) at 30 degrees C and 1.55 x 10(-2) S.cm(-1) at 150 degrees C for x = 0.250)