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dc.contributor.authorYao, Jinhan
dc.description.abstractConsiderable effort has been devoted to the M-N-H system for solid-state hydrogen storage. However, the desorption mechanism is still unclear and the desorption temperature is too high for practical considerations. Here, the desorption characteristics of LiNH2 and a mixture of (LiNH2+LiH) were firstly comparatively studied by simultaneous then-nogravimetry, differential scanning calorimetry and mass spectrometry for further understanding of H2 desorption in the (LiNH2+LiH) system. Mass spectrometry and thermal analysis of (LiNH2+LiH) mixtures indicate that approximately 5 mass % of H2 is released at 180*C after four hours of milling without any apparent release of NH3, whereas insufficient mixing of the two compounds cannot stop the escaping of NH3 from the mixture. Non-unifon-ri mixing can lead to the escape of NH3 from the mixture. The evidence further supports the notion that NH3 intermediated reaction is a possible reaction path within the thermal desorption of the (LiNH2+ LiH) mixture. BN additive, among selected nitrides shows the best effect on desorption from (LiNH2+ LiH). (LiNH2+MgH2)materials with different molar ratios (4: 3,4: 2 and 4: 1) were also studied for their sorption properties and mechanisms. Results show that more than 6 mass% H2 is desorbed from 1500C for the (4LiNH2 +3MgH2)mixture, with two H2peaks at 200 and 320'C. Meanwhile, there is only -5 mass% for (4LiNH2 +2MgH2) mixture with one H2 peak at 200 T. Reversibility measurements suggest that LiNH2 and MgH2 cannot be recovered after absorption; instead, Li2NH and Mg(NH2)2 (or MgNH) take over to perform the H2 storage functions. The (4LiNH2+3MgH2 ) mixture possess a greater H2 capacity in first desorption, but shows less than 2 mass% reversible capacity in subsequent cycles. However, there is only about I mass% capacity loss during the reversibility measurement for the (4LiNH2 +2MgH2)mixture. Other M-N-H systems, mainly NaH, KH, AlH3 and CaH2, were also investigated, and only CaH2 shows the capability of reacting with LiNH2 to produce H2 among these candidates.en_US
dc.subjectMaterials Scienceen_US
dc.titleHydrogen sorption mechanisms in lithium amide and metal hydride reactive systems.en_US
dc.rights.holderThe copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the author

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  • Theses [4217]
    Theses Awarded by Queen Mary University of London

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