Metal Supported Proton Conducting Ceramic Cell with Thin Film Electrolyte for Electrolysis Application

Abstract

Solid oxide fuel cells and electrolysis cells (SOC) have been comprehensively developed as energy conversion and storage devices in recent years. Compared with oxygen ion conducting SOC, proton-conducting ceramic (PCC) cells are more suitable for the operation in the temperature range of 450~650 oC. The reduced operating temperature makes it especially attractive for steam electrolysis application aiming at valorizing waste heat from industrial processes. Moreover, during electrolysis in PCC cells, by design, the water-splitting reaction occurs at the oxygen electrode which enables the production of pure hydrogen at the fuel electrode.Based on previous research on metal-supported solid oxide cells (MS-SOC)[1] at DLR, MS-PCC with thin film electrolyte were investigated in this present study. The low temperature fabrication route (< 1000 °C) was chosen to avoid the serious corrosion of metal substrate at high temperature (1300~1400 °C) which is necessary for making the dense BaZrO3 based electrolyte in traditional sintering routes. In this case, pulsed laser deposition has been used for preparing the 1~2 µm thick electrolyte. Porous ferritic stainless steel, which has been used as the substrate, was cut into a round shape of 18 mm in diameter. To mitigate the Cr diffusion from metal substrate and formation of impurity phase between the metal substrate and NiO/BaZrxCe0.9-xY0.1O3-δ (NiO-BZCY) anode functional layer during processing or operation, Sr-doped LaMnO3 (LSM) was employed as the barrier layer in between. Both LSM and NiO-BZCY layers were processed by lamination of tape-cast thin films onto the metal substrate respectively and successfully co-sintered below 1000 °C. The thermomechanical stability of the thin film electrolyte was investigated by simulating thermal cycles from room temperature up to 950 °C. Platinum and Ba1-xGd0.8La0.2+xCo2O6- δ [2] were considered as oxygen electrode materials. Electrochemical characterization was carried out in both fuel cell and electrolysis operations. Advantages and current limitations of the presented cell design are discussed.Part of this work was supported by the project DAICHI funded by EIG CONCERT-Japan. The German part was funded by the Federal Ministry of Education and Research (project 01DR18002), the Norwegian part funded by the Research Council of Norway (project 284289). The China Scholarship Council is acknowledged for the doctoral scholarship of Haoyu Zheng (201806160173).Figure.1 Scanning electron microscopy (SEM) image of the metal supported proton conducting cells.[1] Costa R., Han F., Szabo P., et al. Fuel Cells, 2018, 18 (3): 251-259.[2] Vøllestad E., Strandbakke R., Tarach M., et al. Nature Materials, Jul, 2019, 18 (7): 752-759. Figure 1