Search results for "ELECTROLYTE"

A chemical and electrochemical multivalent memory made from FeNi3-graphene nanocomposites

2014

FeNi3-graphene nanocomposites present in acetonitrile solutions a redox couple with an electrochemical hysteresis of 2.4 V between the oxidation and the reduction maxima. In view of the high energy required for the reverse transitions, they are here proposed as chemical multilevel memories: permanent, after drying, or erasable in electrolytes, respectively. Keywords: FeNi3-graphene nanocomposites, Voltammetry, Coulovoltammetry, Redox couple, Redox hysteresis

Ab initio modelling of oxygen vacancies and protonic defects in La1−xSrxFeO3−δ perovskite solid solutions

2016

Using hybrid density functionals, detailed ab initio calculations were performed for oxygen vacancies and protons in La1−xSrxFeO3−δ perovskite solid solutions which may serve as a cathode material in protonic ceramic fuel cells. The atomic and electronic structures of different configurations of defects and the role of Fe oxidation state are analyzed in detail. The energetics of the reduction and hydration reactions are investigated. The hydration energy is found to be significantly smaller than for Ba(Zr1−xYx)O3−x/2 electrolyte materials, and the role of basicity as one decisive factor is discussed.

Double cross-linked polyetheretherketone proton exchange membrane for fuel cell

2012

Abstract The proton exchange membrane based on polyetheretherketone was prepared via two steps of cross-linking. The properties of the double cross-linked membrane (water uptake, proton conductivity, methanol permeability and thermal stability) have been investigated for fuel cell applications. The prepared membrane exhibited relatively high proton conductivity, 3.2 × 10 −2  S cm −1 at room temperature and 5.8 × 10 −2  S cm −1 at 80 °C. The second cross-linking significantly decreased the water uptake of the membrane. The performance of direct methanol fuel cell was slightly improved as compared to Nafion ® 117 due to its low methanol permeability. The results indicated that the double cros…

Advances in Anodic Alumina Membranes-based fuel cell: CsH2PO4 pore-filler as proton conductor at room temperature

2009

Abstract Anodic alumina membranes (AAM) filled with cesium hydrogen phosphate proton conductor have been tested as inorganic composite electrolyte for hydrogen–oxygen thin film (≤50 μm) fuel cell (TFFC) working at low temperatures (25 °C), low humidity ( T gas  = 25 °C) and low Pt loading (1 mg cm −2 ). Single module TFFC delivering a peak power of around 15–27 mW cm −2 , with open circuit voltage (OCV) of about 0.9 V and short circuit current density in the range 80–160 mA cm −2 have been fabricated. At variance with pure solid acid electrolytes showing reproducibility problems due to the scarce mechanical resistance, the presence of porous alumina support allowed to replicate similar fuel…

New synthetic strategies for the enhancement of the ionic conductivity in Ce0.8Sm0.2O2-x

2013

Introduction Samarium-doped ceria has been widely investigat-ed for electrochemistry applications as full density elec-trolyte for intermediate temperature solid oxide fuel cells (IT-SOFC), between 500°C and 800°C [1]. One of the main challenges for the ceria-based electrolytes is to decrease the resistivity at the grain boundary zone, especially in this low temperature range. Microstructure and morphology of the powder play a fundamental role on the densification behaviour and grain boundary properties, thus affecting the overall conductivity of electrolytes [2]. In this light, solution combustion syn-thesis (SCS) represents a flexible method to produce ultra fine powders with suitable mic…

Direct measurements of the effects of salt and surfactant on interaction forces between colloidal particles at water-oil interfaces

2007

The forces between colloidal particles at a decane-water interface, in the presence of low concentrations of a monovalent salt (NaCl) and of the surfactant sodium dodecylsulfate (SDS) in the aqueous subphase, have been studied using laser tweezers. In the absence of electrolyte and surfactant, particle interactions exhibit a long-range repulsion, yet the variation of the interaction for different particle pairs is found to be considerable. Averaging over several particle pairs was hence found to be necessary to obtain reliable assessment of the effects of salt and surfactant. It has previously been suggested that the repulsion is consistent with electrostatic interactions between a small nu…

Surface Self-Diffusion and Mean Displacement of Hydrogen on Graphite and a PEM Fuel Cell Catalyst Support

2009

International audience; Quasielastic neutron scattering (QENS) measurements together with equilibrium molecular dynamic (EMD) simulations have been performed to investigate the surface interaction between hydrogen molecules and a carbon material commonly used in polymer electrolyte membrane fuel cells (PEMFC), called XC-72. Half a monolayer of molecular hydrogen was adsorbed on to the carbon material at 2 K. QENS spectra were recorded at the time-of-flight spectrometer IN5 at 40, 45, 50, 60, 70, 80, and 90 K. Simultaneously the pressure was measured as a function of time to monitor the equilibrium surface coverage at each temperature. By using the Chudley and Elliott model for jump diffusio…

Nuovi materiali per celle a combustibile ad ossidi solidi a temperatura intermedia (IT-SOFC): sintesi, caratterizzazione e correlazione struttura-pro…

2014

Life cycle assessment of solid oxide fuel cells and polymer electrolyte membrane fuel cells: A review

2017

Fuel cells (FCs) are among the key technologies that Europe will have to rely on in order to comply with the most recent environmental targets inspired by decarbonization and circular economy. The assessment of the real advantages of using FCs for producing energy must include a reliable analysis of the energy and environmental impacts during the life cycle of these systems, including the raw materials supply, production, use, and disposal. In this context, the life cycle assessment (LCA) is a well-established methodology for assessing the eco-profile of products and services and for identifying the components and the life cycle steps having the largest contribution to energy and environmen…

Amorphous semiconducting passive film-electrolyte junctions revisited. The influence of a non homogeneous density of state on the differential admitt…

2006

Abstract An analysis of the electronic properties of amorphous semiconductor-electrolyte junction is reported for passive films grown on Nb in alkaline solution and in a large range of thickness (~20nm ÷ ~250nm). A modelling of electronic density of state (DOS) has been carried out by fitting EIS spectra, at different potentials and in a range of frequencies (0.1 Hz ≤ f ≤100 kHz), and differential admittance (DA) data of a-Nb 2 O 5 /El interface. The fitting of EIS and DA curves was performed by using the theory of amorphous semiconductor Schottky barrier and a non-homogeneous DOS distribution.