High-performance solid oxide electrolysis cell with the ordered straight pores in the support

Abstract

The large diffusion resistance of steam in the thick support layer is the main factor limiting the performance of solid oxide electrolysis cell (SOEC). This work demonstrates the importance of the straight pore diffusion channel in enhancing the performance of electrolysis cell. The Cell-A with the straight pore diffusion channel in the support and the Cell-B with randomly distributed pores in the support have been compared and the corresponding reaction mechanisms are elucidated. Under 50% absolute humidity (A.H), Cell-A achieves a very high current density of −4.30 A cm−2@1.5V and −2.37 A cm−2@1.3V at 800 °C. Even if under A.H = 10%, Cell-A also displays a high current density of −2.74A cm−2@1.5V, which is 6 times than that of Cell-B. Electrochemical impedance spectroscopy (EIS) measurements and analysis of distribution of relaxation times (DRT) reveal a significant reduction of the gas diffusion resistance on Cell-A. The rate-determining Cell-A is the diffusion of oxygen ion through the air electrode/electrolyte interface, and the gas diffusion is no longer the main factor limiting steam electrolysis.