SOFConvert – Establishing MEA characterisation methods for the optimisation and cost reduction of ceramic cells (MEA) for applications in energy technology

The aim of the project was to raise the performance of the cells manufactured at Kerafol by developing them further and thus reduce costs. In addition, Kerafol staff were trained in Siemens AG at MEA test benches in order to carry out independent measurements. Two test stands were comprehensively modernised and transferred to Kerafol in a newly-installed hydrogen laboratory including the associated infrastructure at the end of the project. Thus Kerafol is in a position to guarantee the quality of the cells manufactured and continue to develop them further.

A benchmark test showed clear room for improvement of the output cells with almost 70 % higher resistance compared to competing cells. To further improve the electrodes, existing paste formulations and their preparation were optimised. In existing uLSM cathodes the polarisation resistance was substantially reduced in this way. In addition the use of new materials was tested and partly established in cell manufacture. In this way cathodes with LSCF were developed, and their considerably lowered resistance yields good cell performance. With self-synthesised LSXM cathode powders of an additional B-level element, homogenous and fine microstructures are achieved at high firing temperatures through a lower sintering activity. Through this the polarisation resistance of the cells were lowered despite higher firing temperature. However the LSXM cathode activated less strongly than the uLSM cathode, so that the cell resistance was not considerably reduced.

On the anode side, through adapted solid contents and the rheology of the pastes the undercoating was made thinner and more impervious. The use of new anode materials through an improved microstructure yielded a considerably enhanced anode performance, lowered polarisation resistance and greater ageing resistance. With cells of the optimised anode and LSCF cathode, an overall resistance of about 250 mΩcm2 was achieved. Stable long-term testing of over 2,500 h and a lower degradation of less than 0.5 % per thermal or redox cycle could be established. With the optimised LSM and LSCF cathodes as well as the Ni-YSZ and Ni-GDC anodes, Kerafol offers three different electrode variations for high performance ESCs, which can be applied to different electrolyte materials and are competitive.