Vacuum Plasma Spraying of Thin-Film Planar Solid Oxide Fuel Cells (SOFC) -Development Status at DLR Stuttgart

摘要

In the SOFC concept developed at DLR Stuttgart, thin-film cells are deposited onto a porous metallic substrate by a multistep vacuum plasma spray process (VPS). The advantages of the metallic substrate supported cells are their high mechanical strength and the ability of rapid thermal cycling. Low internal resistances enable the reduction of the operating temperature to 700-800 °C, the increase of the long-term stability and thus the reduction of the material costs. SOFCs containing different materials, e.g. yttria- and scandia-stabilised ZrO_2, were deposited onto different porous metallic substrates. The VPS process was optimised in order to scale up the cells to a size of 10 cm x 10 cm. The paper focuses on the electrochemical characterisation of the corresponding short-stacks (1-cell in metallic housing) and 2-cell stacks by current/voltage measurements, by impedance spectroscopy and by evaluation of their behaviour during thermal cycling. The influence of the cell supporting substrates and the operating conditions, e.g. gas composition and fuel utilisation, is outlined. This enables to determine the individual losses and to further improve the cell performance in the SOFC stacks.