Interface design for enhancing the performance of solid oxide cell contact layers between interconnects and solid oxide cells

Abstract

In a planar solid oxide cell (SOC) stack, the assembly consists of metal materials and ceramic cells in which various ceramics (such as electrolytes and electrodes) are laminated in multiple layers. Notably, the interface between the air-side electrode and the coated interconnector plays a critical role in determining the performance of the SOC stack, during the manufacturing process. Unlike other SOC cell components, which are typically sintered at high temperature (e.g., over 1000 °C), the contact material at this interface is constructed during the SOC stacking process, generally at a lower temperature range of 750 °C–850 °C. Consequently, the contact material connecting the air electrode and the coated interconnector must exhibit high adhesion and low electrical resistance at 800 °C. In this study, a low-resistance, highly adhesive interface between the air electrode and the interconnector in the SOC stack is developed through diffusion bonding and metal addition at lower temperatures. CoMn spinel oxides are employed as both the contact material and the coating layer, and a concentration gradient is achieved in the contact material and coating layer, with high adhesion and low resistance facilitated by the interdiffusion of Co and Mn. The heat generated during the oxidation of the added metallic Co promotes sintering, further enhancing adhesion. The diffusion bonding interface and the metal-added diffusion bonding interface were subjected to continuous durability tests over 10,000 h, and no deterioration was observed.