Development of Metal Supported Cells Using BaZrO3-Based Proton Conducting Ceramics

Kurzfassung

Solid Oxide Cells (SOC) have demonstrated many potential applications in electrochemical conversion with high efficiency and stability for long term operation. In the European project EVOLVE (FCH JU Grant 303429 - 2012/2017), a porous Metal Supported (MS)-SOC implementing a multilayer thin-film electrolyte manufactured by physical vapor deposition technique has been successfully demonstrated [1]. Here we present our first result in the development of planar MS-Proton conducting Ceramic Cells (PCC) in the project DAICHI funded by EIG CONCERT-Japan (2018/2021), based on the expertise in MS-SOC. PCCs demonstrate high potentials in many electrochemical applications because of its geometrical advantage that enables pure hydrogen supply or production in fuel cell or steam electrolysis operations, respectively, and can therefore prevent fuel dilution and reduce degradation problems in Ni-based anodes. However, the drawback of state-of-the-art proton conducting materials relies in their highly refractory nature requesting high sintering temperature, which raises the hurdle in upscaling in size sintered cells. Known as the third generation cell architecture, MS cells offer intrinsically superior mechanical strength, tolerance towards thermal cycles and cost reduction by replacing expensive ceramic based supporting materials with cheap ferritic stainless steel. The challenge is to find a feasible process in the fabrication of gas-tight PCC electrolyte on the MS without a high temperature thermal treatment, typically above 1400 °C. In this work, Pulsed Laser Deposition (PLD) technique was employed to fabricate thin and dense coating of perovskite-type PCC electrolytes. As a model electrode, which coating process is well developed, a 20 µm-thick La0.8Sr0.2MnO3 (LSM) electrode layer was fabricated on porous metal substrates with pore size of a few tens of µm by laminating technique, followed by wet coating process of two intermediate electrolyte layers (IL). The pore size is gradually reduced from a few tens of µm (MS) to below a hundred nm (IL) before PLD. On the top of nano-porous ILs, a thin-film BaZrO3-based perovskite PCC electrolyte layer was deposited using PLD (thickness below 2 µm). The results demonstrated that dense and crack-free MS-PCC cells can be obtained in an optimal PLD condition and with all the processes under 1000°C. The results of structural and impedance analyses are presented and critically discussed to validate the potential of developed MS-PCC. [1]: F. Han, R. Costa, R. Semerad, patent application DE102016112125 (A1), pending