SOFC-LIFE

Solid Oxide Fuel Cells – Integrating Degradation Effects into Lifetime Prediction Models

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 Obiettivo del progetto (Objective)

'Long-term stable operation of Solid Oxide Fuel Cells (SOFC) is a basic requirement for introducing this technology to the stationary power market. Degradation phenomena limiting the lifetime can be divided into continuous (baseline) and incidental (transient) effects. This project is concerned with understanding the details of the major SOFC continuous degradation effects and developing models that will predict single degradation phenomena and their combined effect on SOFC cells and single repeating units. The outcome of the project will be an in-depth understanding of the degradation phenomena as a function of the basic physico-chemical processes involved, including their dependency on operational parameters. Up to now research has rarely succeeded in linking the basic changes in materials properties to the decrease in electro-chemical performance at the level of multi-layer systems and SOFC cells, and even up to single repeating units.'

Introduzione (Teaser)

Solid oxide fuel cells (SOFCs) are a promising and clean alternative to pollution-producing engines. Scientists are characterising degradation mechanisms sosuch that designs can be improved for greater market penetration.

Descrizione progetto (Article)

Solid oxide fuel cells (SOFCs) convert the chemical energy in fuels into electrical energy. They can use a wide variety of fuels to produce electricity with very high efficiency, no moving parts and virtually no noise or chemical pollution. While they are poised for large-scale commercial implementation, SOFCs are limited by degradation phenomena that reduce their service lifetimes.

In an effort to overcome responsethis challengeTo investigate degradation mechanisms, scientists initiated the EUC-funded project 'Solid oxide fuel cells: Integrating degradation effects into lifetime prediction models' (SOFC-LIFEife). Investigators are combining experimental and theoretical work to enhance understanding of continuous degradation mechanisms, and to optimise predictive models of individual and combined processes.

Individual fuel cells consist of two electrodes, the cathode and the anode, separated by a solid electrolyte. In order to deliver enough power, multiple cells are connected to form a fuel cell stack. SOFC-LIFEife has deconstructed the SOFC stack into isolated elements and interfaces exposed to typical conditions of SOFC system operation. These components are evaluated at regular time intervals for a time-lapse approach to anode-side phenomena and cathode-side phenomena.

Careful consultation with industrial partners led to the definition of materials and testing protocols for both anode- supported cells (ASCs) and electrolyte- supported cells (ESCs). Testing parameters included the three different values of temperature, current density and humidity. Both anode-side and cathode-side testing is underway, elucidating important relationships among conductivity, temperature and humidity. Extensive post-test examinations were initiatedhave begun to quantify morphological changes in microstructure with time. Experimental methods consist of light microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), three-dimensional (3D) focussed ion beam (FIB) sequential sectioning and three-dimensional3D tomography.

Scientists have also begun the development of the predictive numerical tools combining physical models, empirical models and the computation of electrode- efficient parameters. The electrochemical model is continuously being compared with electrochemical characterisations to isolate effects on the anode and cathode sides of the SOFC and derive functional descriptions of physical and chemical changes.

SOFC-LIFEife plans to deliver high-level models capable of predicting single degradation phenomena and their combined effects on SOFCS cells and single repeating units for the improved longevity of SOFCs.