文章信息/Info

Title:

Excellent effects of composite additives MgF2@C on hydrogen release properties of LiBH4

作者:

彭丹丹; 郭亮亮; 韓樹民

燕山大學環境與化學工程學院

Author(s):

PENG Dandan;  GUO Liangliang;  HAN Shumin

School of Environmental and Chemical Engineering ，Yanshan University

關鍵詞:

儲氫材料; MgF2@C; LiBH4; 儲氫性能; 催化摻雜

Keywords:

Hydrogen storage material;  MgF2@C;  LiBH4;  Hydrogen storage property;  Catalytic doping

?

DOI:

10.7502/j.issn.1674-3962.2017.11.03

文獻標志碼:

A

摘要:

LiBH4作為一種最具潛力的高容量儲氫材料，存在著放氫溫度高、放氫速率慢和可逆性差等問題。本文采用高溫碳化法得到復合添加劑MgF2@C，同時對比研究了該添加劑和MgF2對LiBH4儲氫性能的影響。研究表明，含F添加劑MgF2能促使LiBH4熱力學失穩，從而大幅改善體系的儲氫性能。碳骨架的存在保證了儲氫基體在高溫條件下不團聚且不與添加劑分離，高度分散的MgF2能夠極大增大體系反應活性位點，促進氫在其表面的解離與重組，提高催化效率。結果表明，MgF2@C可使LiBH4的初始放氫溫度和放氫峰值溫度分別降低100 ℃和86 ℃，且最終放氫量能夠達到6.58 wt.%。并且，在等溫放氫過程中，LiBH4-MgF2@C復合儲氫材料的放氫速率是LiBH4-MgF2復合體系的3倍。

Abstract:

Lithium borohydride (LiBH4) has gained extensive attention as potential hydrogen storage media, however, high thermodynamic stability, slow kinetics, and limited reversibility are still major hurdles. In this paper, high-dispersed MgF2@C was successfully synthesized via carbonization process at high temperature, and a series of work have been taken for the influences of MgF2 and MgF2@C on LiBH4. Microstructure analyses reveal that the MgF2 could cause F, and then accelerate the thermodynamic instability for LiBH4, therefore, improving the hydrogen storage property. This fundamental understanding provides us with that the exist of carbon skeleton could prevent the aggregation of the composite or separation for the additive in the de/hydrogenation process at high temperature, and the high-dispersed MgF2 could provide more reactive sites, which greatly increase the dissociation and restructuring for H2, improving the catalytic efficiency. Temperature programmed desorption (TPD) analyses show that MgF2@C could reduce the onset temperature and the peak temperature for 100 ?C and 86 ?C, respectively, and the final hydrogen desorption capacity reaches 6.58 wt.%, indicating that the addition of MgF2@C is not significantly reduce the hydrogen capacity. In the process of isothermal hydrogen desorption, the rate of LiBH4-MgF2@C composite is three times of LiBH4-MgF2@C.