Contact corrosion resistance between the cathode and current collector plate in the molten carbonate fuel cell

The corrosion layer Formed in the contact between the cathode and the curre nt collector is one factor limiting the cathode performance in molten carbo nate fuel cells (MCFC). In order to investigate the contribution to the tot al polarization of the contact resistance, electrochemical experiments were performed in a laboratory-scale fuel cell unit with a specially designed c urrent collector. Two cathode materials, NiO and LiCoO2, were investigated to elucidate the impact of the cathode material on the formed corrosion lay er. Polarization measurements as well as electrochemical impedance spectros copy were used. The method works well for NiO electrodes. However, due to t he poor electronic conductivity in the LiCoO2 electrode, the experimental r esults become difficult to evaluate due to a nonuniform potential distribut ion. The contact resistance between the cathode and the current collector c ontributes with a large value to the total cathode polarization. The corros ion layer in case of the LiCoO2 cathode was iron-rich and has a thickness o f about 20 mum after 8 weeks operation of the fuel cell. Ln the case of the NiO cathode, a nickel-rich corrosion layer of about 15 mum was formed afte r 5 weeks operation of the fuel cell. (C) 2000 The Electrochemical Society. S0013-4651(00)01-079-9. All rights reserved.