Energy storage and hydrogen production by proton conducting solid oxide electrolysis cells with a novel heterogeneous design

Abstract The proton-conducting solid oxide electrolysis cell is a promising technology for energy storage and hydrogen production. However, because of the aggressive humid condition in the air electrode side, the stability of electrolysis cells is still a concern. In addition, the energy efficiency needs further improvement before its practical application. In this work, considering both stability and energy efficiency, a novel heterogeneous design is proposed for proton-conducting solid oxide electrolysis cells. In this heterogeneous design, the merits of proton-conducting materials can be taken advantage of and the drawbacks of proton-conducting materials can be circumvented synchronously, resulting in better stability and higher efficiency of electrolysis cells. The feasibility and advantages of the heterogeneous design are demonstrated in electrolysis cells with yttrium and zirconium co-doped barium cerate-nickel as the fuel electrode material and yttrium-doped barium zirconate as the electrolyte material by experiment and modeling. The experimental results demonstrate that compared with the conventional homogeneous design, this novel design can efficiently improve the proton conductivity of the yttrium-doped barium zirconate electrolyte (from 0.88 × 10−3 S cm−1 to 2.13 × 10−3 S cm−1 at 873 K) and slightly improve the ionic transport number of the electrolyte (from 0.941 to 0.964 at 873 K), resulting in better electrochemical performance. The electrolysis cells with this design also show good stability. Moreover, the simulation results show that the faradaic efficiency and energy efficiency of electrolysis cells are improved by applying this novel design. These impressive results demonstrate that heterogeneous design is a rational design for high-performance and efficient proton-conducting solid oxide electrolysis cell.