| Molten carbonate fuel cell (MCFC) is beIieved to be one of the most promising devices usedfor power pIant in future, due to its high efficiency, negligible poIIution, unnecessary use ofnoble metal as catalyst, simp1e structure of power plant and other advant8ges. So far it has beenapplied pre1iminarily to the power plants in commercial sca1e. However, the relatively short celllife, mainIy resulting from the dissolution of NiO cathode and corrosion of materials in MCFC,limits severely its further commercialization. Since the generation of MCFC, large numbers ofefforts have been incessantly made to investigate on the various technical problems related toMCFC. At present, the MCFC industry has a rapid development and great success; neveftheless,there are still some problems to be 5olved, especia11y those about complicated cathode system.Making a comprehensive view of the cathode studies, we find that the following four problemskeep unclear so far and need to be further investigated.(l) The mechanism of cathode reaction under MCFC operation, especially the variety ofcrucial intermediate -- active oxygen species, is always controversia1 and has not cometo an agreement. The restriction and lack of experimental method and apparatus are themost important cause resulting in an ambiguity in the study of cathode reactionmechanism. Although the traditiona1 electrochemical measurement is a unique techniqueto acquire the dynamic para1neters of reactions in MCFC, it seems to be macroscopicaland indirect to determine the existence and variety of intermediate oxygen species.(2) Similarly, the research into the mechanism of dissolution and deformation of NiO cathodeis basica1ly limited in a macroscopic and indirect range. Some main apparent factorsinvolved in the dissolution and deformation process, such as melts composition,atmospheres and temperature etc have been studied, but the reIated details and furtherexperimental evidences in a molectlIar Ievel are absent and difficult to be obtained atpresent.(3) Despite of many studies on oxidationjlithiation of porous nickel, a very important factorAbstracthas not been pay much 8ttedion to, that is, most of the matCria[s in MCFC actually workunder a Ioad generated by the self weight of MCFC stack, which undoubtedly has a greateffect on the materials performance in MCFC.(4) The cathode improvement through modification to old cathode and development of newsubstitute cathodes are the most direct means to slowdown the dissolution anddeformation of cathode materials and prolong the cell life. A series of composite andsubstitute cathode materials have been exploited. Even so, the materials sti1l have a fardistance to reach the actual industrial requirements, when being taken into account oftheir performance, costs and practical installation.The above-mentioned problems are correlated and dependent c1osely each other, whosesettIement wiII generate definitely vital promotion to MCFC industry Accordingly, the thesisfocuses on (1) in situ spectroscopic studies of cathode reaction mechanism in MCFC, (2)development of the novel research methods and experimental aPparatuses fOr in situ monitoringthe cathodic process of NiO cathode; (3) further eIucidation to the mechanisms about dissoIutionand deformation of NiO cathode, and exploration of the new approach to lowdown thedissolution and defOrmation of NiO cathode in MCFC.(i) In situ spectroscopy of the intermediate oxygen specics in cathode rcaction ofMCFCThe cIarification of cathode reaction mechanism is a very important theoretical direction toimprove MCFC performance and to develop new catl1ode materials. lt has been recognized thatthe in situ revelation of intermediate oxygen species generated by the reaction of oxygen withmoIten carbonate is a crucial importance in the mechanistic study. Bllt only a little progress hasbeen made in mechanistic study of cathode process due to its compIication in MCFC con...
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