Chapter 7 - Interconnect

Abstract

This chapter discusses the interconnect regarding a solid oxide fuel cell (SOFC). The primary function of the SOFC interconnect is to connect the anode of one cell to the cathode of the next cell in electrical series. It also separates the fuel from the oxidant in adjoining cells of a stack. Thus, the interconnect material should be stable in both the reducing and oxidizing environments, impermeable to gases, and sufficiently conductive to support electron flow at the operating conditions. Because the SOFC operates at high temperatures (600º to 1000 ºC) the interconnect must be chemically and thermally compatible with the other cell components from room temperature to those operating temperatures, and to even higher temperatures at which the fuel cell is fabricated. The key requirements for the interconnect in the SOFC are stability, conductivity, compatibility, thermal expansion, and porosity, Oxide ceramics, metals may be used as SOFC interconnect, especially for the flat-plate design. The advantages of metallic interconnects include better chemical compatibility, improved mechanical properties, and lower cost. The primary concerns regarding metallic interconnects are thermal expansion mismatch with other cell components and long-term instability (oxidation, corrosion) under fuel cell operating conditions. High-temperature alloys have also been considered as interconnect material, especially for fiat-plate SOFCs. Currently, LaCrO3 is the most common interconnect material for SOFCs.