Pitch and TiB2/C green composite cathode material were respectively analyzed with simultaneous DSC-TGA, and effects of three baking processes of TiB2/C composite cathode material, i.e. K25, K5 and M5, on properties of...Pitch and TiB2/C green composite cathode material were respectively analyzed with simultaneous DSC-TGA, and effects of three baking processes of TiB2/C composite cathode material, i.e. K25, K5 and M5, on properties of TiB2/C composite cathode material were investigated. The results show that thermogravimetrie behavior of pitch and TiB2/C green composite cathode is similar, and appears the largest mass loss rate in the temperature range from 200 to 600 ℃. The bulk density variation of sample K5 before and after baking is the largest （11.9%）, that of sample K25 is the second, and that of sample M5 is the smallest （6.7%）. The crushing strength of sample M5 is the biggest （51.2 MPa）, that of sample K2.5 is the next, and that of sample K5 is the smallest （32.8 MPa）. But, the orders of the electrical resistivity and electrolysis expansion of samples are just opposite with the order of crushing strength. The heating rate has a great impact on the microstructure of sample. The faster the heating rate is, the bigger the pore size and porosity of sample are. Compared with the heating rate between 200 and 600℃ of samples K25 and K5, that of sample M5 is slower and suitable for baking process of TiB2/C composite cathode material.展开更多
Mg （MgH2）-based composites, using carbon nanotubes （CNTs） and pre-synthesized titanium based complex （TCat） as the cat- alysts, were prepared by high energy ball milling technique. The use of both catalysts demo...Mg （MgH2）-based composites, using carbon nanotubes （CNTs） and pre-synthesized titanium based complex （TCat） as the cat- alysts, were prepared by high energy ball milling technique. The use of both catalysts demonstrated markedly improved the hydrogen storage performance, e.g. a significant increase of hydrogen release rate and decrease of desorption temperature. The synthesized composites can absorb almost 6 wt% of hydrogen within 3 min at 200 ~C and desorb 6 wt% hydrogen in 10 min at 310 ~C. The influence of CNTs and TCat on desorption temperature was also investigated by using temperature programmed desorption （TPD）. The TPD results reveal that the peak desorption temperature and the onset temperature can be lowered by 109 ~C and 155 ~C, respectively, compared to the non-catalyzed MgH2. The reaction enthalpy and entropy of hydrogen de- sorption for the synthesized MgH2-based composites are calculated by the van＇t Hoff analysis to be 73.1 kJ/mol H2 and 130.2 J/mol H2 K, respectively.展开更多
基金Project (2005CB623703) supported by the Major State Basic Research and Development Program of ChinaProject (2008AA030502) supported by the National High-Tech Research and Development Program of China
文摘Pitch and TiB2/C green composite cathode material were respectively analyzed with simultaneous DSC-TGA, and effects of three baking processes of TiB2/C composite cathode material, i.e. K25, K5 and M5, on properties of TiB2/C composite cathode material were investigated. The results show that thermogravimetrie behavior of pitch and TiB2/C green composite cathode is similar, and appears the largest mass loss rate in the temperature range from 200 to 600 ℃. The bulk density variation of sample K5 before and after baking is the largest （11.9%）, that of sample K25 is the second, and that of sample M5 is the smallest （6.7%）. The crushing strength of sample M5 is the biggest （51.2 MPa）, that of sample K2.5 is the next, and that of sample K5 is the smallest （32.8 MPa）. But, the orders of the electrical resistivity and electrolysis expansion of samples are just opposite with the order of crushing strength. The heating rate has a great impact on the microstructure of sample. The faster the heating rate is, the bigger the pore size and porosity of sample are. Compared with the heating rate between 200 and 600℃ of samples K25 and K5, that of sample M5 is slower and suitable for baking process of TiB2/C composite cathode material.
基金supported by the Australian Research Council(ARC)
文摘Mg （MgH2）-based composites, using carbon nanotubes （CNTs） and pre-synthesized titanium based complex （TCat） as the cat- alysts, were prepared by high energy ball milling technique. The use of both catalysts demonstrated markedly improved the hydrogen storage performance, e.g. a significant increase of hydrogen release rate and decrease of desorption temperature. The synthesized composites can absorb almost 6 wt% of hydrogen within 3 min at 200 ~C and desorb 6 wt% hydrogen in 10 min at 310 ~C. The influence of CNTs and TCat on desorption temperature was also investigated by using temperature programmed desorption （TPD）. The TPD results reveal that the peak desorption temperature and the onset temperature can be lowered by 109 ~C and 155 ~C, respectively, compared to the non-catalyzed MgH2. The reaction enthalpy and entropy of hydrogen de- sorption for the synthesized MgH2-based composites are calculated by the van＇t Hoff analysis to be 73.1 kJ/mol H2 and 130.2 J/mol H2 K, respectively.
