Investigation On The Rehydrogenation Anddehydrogenation Of Libh₄ By Adding Single-walled Carbon Nanotubes

With the development of industrialization, people has a growing demand for energy. Hydrogen energy is causing widespread concern to every country as green,rich energy. The most crucial issue of hydrogen using is the problem of hydrogen storage. The hydrogen content of LiBE4 is as high as 18.4wt%,which is very high in the known hydrogen storage materials. So LiBH4 can serve as an excellent hydrogen storage medium, being the people's attention.In this paper, LiBH4 was used as experimental starting materials, laboratory-made SWNTs as additive, activating and mixing them by mechanical milling method.The samples changing in the hydrogenated state were also examined by hydrogen storage performance testing device, draw the curve of hydrogen storage performance tested;Using (TG/DSC/MS) synchronous thermal analyses tested thermodynamics decomposition process and decomposition peak temperature in the process of rehydrogenation and dehydrogenation;Using XRD,SEM,TEM to measure and characterize the composition, phase structure, morphology and microstructure before and after the process of rehydrogenation and dehydrogenation for the sample.The comparative experiment of hydrogen storage performance testing indicated that adding 30wt%SWNTs and milling 1h would be better for LiBH4.Hydrogen storage performance testing and synchronous thermal analyses indicated that adding laboratory prepared SWNTs to LiBH4 can promote the kinetics of rehydrogenation and dehydrogenation, LiBH4-30wt%SWNTs released 4.3wt%,9.1 wt%,10.8wt% hydrogen and released 1.4wt%,3.8wt%,5.7wt% hydrogen within 30min,lh,2h respectively;The system cycle capacity loss also reduced, the previous two cycles of dehydrogen LiBH4 degraded 72.6%, while the LiBH4-30wt%SWNTs degraded by 56.9%;LiBH4-30wt%SWNTs dehydrogenate at around 280℃,releasing much of hydrogen at the temperature 382℃,402℃and 424℃, but there is only one dehydrogenation peak in pure LiBH4 and the temperatures as high as 465℃.XRD detection showed that there were metal nano-particles in SWNTs (prepared in the laboratory).But when the purified SWNTs was added into LiBH4 we found that the catalytic performance will be reduced by hydrogen storage performance testing,so metal nanoparticles and SWNTs all have catalytic performance for LiBH4.XRD detection also indicated that the decompositing reaction of LiBH4 was not completely.SEM photographs indicated that melting-induced generated in the process of rehydrogenation and dehydrogenation, made the grain growth and agglomeration caking,but SWNTs reduced the negative effects of melting-induced. SWNTs can form a network structure, the sample is divided into a lot of micro-area make the reaction more completely. TEM analysis showed that SWNTs tubes assembly and SWNTs tube bundles are also micro-defect,so SWNTs can also absorb a certain amount of hydrogen, thereby increasing the system's hydrogen storage capacity.