Marie Wandel

Performance and Electrochemical Characterisation of Thin Electrolyte SOFCs

The performance and electrochemical behavior of two anodesupported thin electrolyte cells, with different manufacturing parameters, is determined by polarization measurements and electrochemical impedance spectroscopy (EIS). In addition to characterization, a previously suggested equivalent circuit consisting of a series resistance (Rs) and five arcs to describe the polarization resistance of the cell is tested. The aim is to breakdown and assign the losses to each individual cell component around open circuit voltage at selected temperatures. As will be seen, the proposed in-depth electrochemical characterization can provide valuable guidelines for production/performance optimization.

Status of Development and Manufacture of Solid Oxide Fuel Cell at Topsoe Fuel Cell A/S and Riso̸/DTU

and Risø/DTU DTU Orbit (01/04/2019) Status of Development and Manufacture of Solid Oxide Fuel Cell at Topsoe Fuel Cell A/S and Risø/DTU Fuel Cell (TOFC) provides the SOFC technology platform: Cells, stacks, and integrated stack module for different applications and collaborates with integrator partners to develop, test and demonstrate SOFC applications. The technology development is based on a R&D consortium with Risø National Laboratory (Risø/DTU) which includes material synthesis and cost effective ceramic manufacturing methods for anode and metal supported flat planar cells in addition to multilayer assembling for compact stacks with metallic interconnects. The development is focussing on high electrochemical performance and durability as well as maximal robustness. In 2008 TOFC has constructed a 5 MW/year cell and stack production facility in Denmark featuring all the necessary unit operations from ceramic powder, continuous tape casting, screen printing, spray painting and sintering to complete stack modules. TOFCs engagement in SOFC technology includes system development in collaboration with system partners and development and manufacturing of integrated stack assemblies called PowerCore. ©2009 COPYRIGHT ECS The Electrochemical Society

Electrochemical Impedance Studies of SOFC Cathodes

Mixed ion- and electron-conducting composite electrodes consisting of doped ceria and perovskite have been studied by electrochemical impedance spectroscopy (EIS) at different temperatures and oxygen partial pressures. This paper aims to describe the different contributions to the polarisation impedance of the cathode at intermediate operating temperatures. The perovskite is of the La-Sr-Co-Fe type. The EIS response of symmetrical cells with a thick (~200 µm) gadolinia doped ceria electrolyte was compared with the impedance contribution of the cathode of a full anode supported cell. The full cells had a Ni-YSZ anode and anode support, a thin YSZ electrolyte, and a CGO barrier layer. The symmetric and full cell cathode responses were compared at open-circuit voltage. Humidified hydrogen was used as the fuel in the full cell measurements. Differential analysis of the impedance data was used to identify frequency ranges where changes occur upon degradation and oxygen partial pressure variations.

Nonlinear germanium nanocluster doped planar waveguides

In future all-optical networks pure optical signal processing, such as switching, routing and signal regeneration is going to be essential. Each of these tasks puts different constraints to the chosen solution regarding speed, wavelength range of operation, noise and polarization properties etc. However, a large fraction of these functionalities may be obtained by utilizing optical components with a strong nonlinear refractive index [1]. Silica has a very low nonlinear refractive index. Fortunately, silica also has a very low loss. As a consequence of the latter a significant nonlinear phase shift may be accumulated over a large distance i.e. over tens of kilometers of optical fiber. Because of this long length silica is not a viable material when designing compact nonlinear planare lightwave circuits. Recently, nanostructured materials have been proposed as promising candidates for nonlinear waveguides. More specifically glass based materials doped with nanometer sized clusters of for example metals or semiconductors. In this work we demonstrate processing of waveguides with strong confinement of the electrical field achieved using air trenches and processing of glass doped with germanium nanoclusters. We illustrate how the cluster size may be controlled and we show that realization of nonlinear waveguides may be within reach.