Preparation of functional layers for anode-supported solid oxide fuel cells by the reverse roll coating process

The roll coating technique represents a novel method for applying functional layers to solid oxide fuel cells (SOFCs). This fast process is already used for mass production in other branches of industry and offers a high degree of automation. It was utilized for coating specially developed anode (NiO + 8YSZ, 8YSZ: 8 mol% yttria-stabilized zirconia) and electrolyte (8YSZ) suspensions on green and pre-sintered tape-cast anode supports (NiO + 8YSZ). The layers formed were co-fired in a single step at 1400 °C for 5 h. As a result, the electrolyte exhibited a thickness of 14–18 μm and sufficient gas tightness. Complete cells with a screen-printed and sintered La0.65Sr0.3MnO3−δ (LSM)/8YSZ cathode yielded a current density of 0.9–1.1 A cm−2 at 800 °C and 0.7 V, which is lower than the performance of non-co-fired slip-cast or screen-printed Jülich standard cells with thinner anode and electrolyte layers. The contribution of the cell components to the total area-specific resistance (ASR) was calculated by analyzing the distribution function of the relaxation times (DRTs) of measured electrochemical impedance spectra (EIS) and indicates the potential improvement in the cell performance achievable by reducing the thickness of the roll-coated layers. The results show that the anode-supported planar half-cells can be fabricated cost-effectively by combining roll coating with subsequent co-firing.

► Roll coating is a new industrial manufacturing route for coating SOFC layers.
► Green tapes and pre-sintered substrates were coated at ∼5 m min−1.
► 8–13 μm anode layers and 14–18 μm electrolytes were manufactured.
► With LSM cathodes, the cells yielded 0.9–1.1 A cm−2 (0.7 V, 800 °C, H2).
► Anode and electrolyte must be thinner to compete completely with standard cells.