Development of materials for electrodes, electrolytes and bipolar plates which will not be corroded and which will allow the operation of molten carbonate fuel cells for 20000-40000 hours.
The work performed by CISE (Milan, I) deals with the following subjects:
(1) the study of electronic surface properties of pure and doped NiO and of the intercalation between selected NiO crystals and gases versus temperature and exposure; (2) electrochemical tests in home-made MC half-cells aimed to verify the effectiveness of surface treatments (thin e-beam evaporated films) and of selected dopants on the electrocatalytic properties and on the dissolution resistance of lithiated nickel oxide cathodes.
At ZSW-ECW in Stuttgart (D), investigations on electrode of alternative materials with extended lifetime, adequate performance, simple fabrication and formation have been performed. Besides R&D on MCFC cathodes headed for the replacement of lithium-doped nickel oxide by other mixed oxides such as LiFeO2, NiFeO4, Co2TiO4 and NiWO4, by checking their behaviour in the carbonate melt. A method of standardised anode shrinkage measurement had been worked out in order to attack the predominant problem of structural stability.
Investigation on alternative MCFC cathodes materials have been carried out at the Netherlands Energy research Foundation ECN (Petten, NL). Attention has been given to synthesis of ceramic powder, fabrication of porous cathode structures, intrinsic material properties, and behaviour in small scale MCFC. A final assessment has been made, resulting in one promising candidate material: LiCoO2. It is recommended to develop this material for large-area cathodes for MCFC.
Mathematical models for porous electrodes have been derived, analysed and testing at Technische Universiteit Delft - TU DELFT (Delft, NL), with the purpose to maximise the performance of MCFC. The models were fitted to polarisation and impedance measurements performed on 3 sq.cm. MCFC lab-cells. The reaction mechanism and kinetics is important input information for the models and was studied in half-cell experiments using Chrono-Amperometry and Impedance Spectroscopy. A new porous electrode models (three phase homogenous model) was developed and fitted to the AC-impedance data yielding realistic parameter values.
R & D activities aimed to set-up a suitable protecting coating against corrosion of cell and stack metallic components in wet-seal are have been performed by ANSALDO Ricerche (Genova, I); the IVD technique and the subsequent diffusion bonding heat treatment have been successfully developed for 1 ft2 stack separator plates. Alternative candidate materials to Aisi 316 s.s. for use in stack metallic components, has been tested by out-of-cell corrosion tests and in mcfc operating conditions (100 sq.cm bench cell); Incolloy 825 showed the best corrosion resistance.
Molten carbonate fuel cells have the promise of producing electricity from methane, coal or oil with a 50-60% efficiency and a pollution which is 10-100 times lower than for conventional systems. MCFC operate at 650 C they produce high temperature waste heat; this makes them very suitable for co-generation applications. The main problem is to develop components which do not corrode or disintegrate in the very corrosive atmosphere with molten salts at 600-680 C.
The problem of the dissolution of the nickel oxide cathode by the carbonate electrolyte will be dealt with in two ways: improvement of the nickel oxide cathode (CISE) and development of new cathode materials (ECN and TU Delft). A number of non-conventional porous materials for electrodes and electrolytes will be explored by ZSW and ANSALDO will investigate corrosion resistant steels for the bipolar plates.
Funding SchemeCSC - Cost-sharing contracts
20090 Segrate Milano
2628 BL Delft