NiO Dissolution in Molten Carbonate Fuel Cells: Effect on Performance and Life

Abstract

The short-circuit phenomenon caused by dissolution of the NiO cathode in the molten carbonate fuel cell was experimentally investigated. Monitoring CQ concentration in the anode exhaust gas can be an effective way to detect cell short circuit. The effects of matrix thickness and cathode CQ partial pressure on shorting were elucidated. The time-to-initialshort-circuit (shorting time) is approximately proportional to the second power of the matrix thickness and the reciprocal of the cathode CO2 partial pressure. This can be explained by the relationship between conductance of the short circuit and the Ni-content of the matrix. A simple mode] to correlate the conductance with the shorting time was developed. It is concluded that part of the deposited Ni exists as lithiated NiO.

Charge and Mass Transfer on a La2O3 Added Li/Na or Li/K Molten Carbonate Meniscus Electrode of LaNiO3 Coated Au Ring for Oxygen Reduction Reaction

“…[2], [3] and [4] as follows: The value of  c evaluated from Allen-Hickling plots was 0.34, the a and b of reaction order in the eqs. [4] and [5] were 0.31 0.08 and -0.35  0.04, respectively. So the reaction on LaNiO 3 for the ORR might be competed mechanism of POP and PCP.…”

“…The MCFC system can use various fuels without precious metal, and has higher energy conversion efficiency compared with room temperature fuel cells such as polymer electrolyte fuel cell (PEFC) systems (3). Pressurized MCFC system has higher efficiency than ambient pressure one, but it has a serious problem in lifetime caused by dissolution of NiO cathode into the electrolyte and the internal short-circuit of Ni (Ni shorting) (4).…”

Development of Molten Carbonate Fuel Cells in Japan and at CRIEPI - Application of Li/Na electrolyte -

“…This phenomenon should therefore be avoided during the regular lifetime of the cells. CRIEPI has tested many cells under various pressure conditions with various cell specifications and found that the time to start short-circuiting is mainly determined by the cathode CO 2 partial pressure and the matrix thickness [17]. The relationship is expressed as follows:…”

Fuel cell power system applications in Japan

“…Reduced nickel particles form internal short-circuiting bridges within the electrolyte matrix. Since the shorting time relates to the partial pressure of carbon dioxide at the cathode side, based on CRIEPI's experiments (8), it could be traded off subject to setting the operation pressure which affects cell voltage directly. Electrolyte loss is caused mainly by corrosion, as well as by creepage and vaporization.…”