Enhanced hydrogen generation by hydrolysis of LiBH_4 doped with multiwalled carbon nanotubes for micro proton exchange membrane fuel cell application

摘要

LiBH_4 has a high hydrogen storage capacity and could potentially serve as a superior hydrogen storage material. However, during the hydrolysis process for hydrogen generation, the agglomeration of the hydrolysis product of LiBH_4 limits its full utilization. In order to completely release the stoichiometric amount of H_2 from LiBH_4 hydrolysis, multiwalled carbon nanotubes (MWCNTs) were doped with LiBH_4 by mechanical milling. The results show that MWCNT carried LiBH_4 can slowly react with water vapor at room temperature which is 25 C lower than the reaction temperature of neat LiBH_4. Agglomeration can be avoided when the addition of MWCNTs exceeds 7 wt.%, which results in a complete hydrolysis process. The total hydrogen capacity is 7.5 wt.%. The enhanced hydrolysis of LiBH_4 can be attributed to the MWCNTs which increased the contact areas between LiBH_4 and water and created gas channels for hydrogen diffusion. The performance of a micro proton exchange membrane fuel cell connected to MWCNT-doped UBH_4 powder packed-bed reactor was examined. The result demonstrates that doping with MWCNTs enhanced the hydrogen generation of LiBH_4 hydrolysis. MWCNT-doped LiBH_4 can be applied as hydrogen source of fuel cells.