Cold sintering of proton-conducting half cells based on BaZr0.7Ce0.2Y0.1O3-δ/NiO

Electrochemical devices based on proton conducting ceramic oxides have shown a high potential for conversion processes at intermediate temperatures. In these cells, perovskite ceramics like BaZr0.7Ce0.2Y0.1O3-δ (BZCY), which are based on the solid solution of BaZrO3 and BaCeO3 doped with Y, have proven to be a good compromise between chemical stability and proton conductivity. However, the refractory nature of this material system requires high sintering temperatures to enable dense ceramic membrane layers. Recently, a novel processing route, which applies the cold sintering process (CSP) as a pre-densification step has been developed allowing to lower the sintering temperatures while maintaining excellent electrochemical properties. In this study, we further improved this method by implementing a BZCY/NiO support layer for BZCY. After final thermal treatment under reducing conditions, a dense BZCY membrane supported by a porous BZCY/Ni electrode support resulted. We show that using powder processing techniques, it is possible to sinter thick layered structures, consisting of an almost dense, phase pure perovskite BZCY layer and a porous BZCY/NiO layer. Furthermore, the NiO phase was successfully reduced to Ni by an additional thermal treatment at 900 °C in Ar/H2. The focus of this study was to generally prove the feasibility of applying co-cold sintering for the processing of layered ceramic architectures, which can be used – after further optimization of the processing – as electrode supported fuel or electrolysis cells.