石墨炔类结构储锂性能的第一性原理研究

Lithium Storage on Extended Graphynes: Predicted by DFT Calculations

基于密度泛函理论的第一性原理的计算方法,研究了石墨炔类结构的储锂性能,结果表明,石墨炔类体系是一种理想的储锂材料,锂原子通过向衬底转移电荷而带正电,彼此之间的库仑排斥作用避免了锂原子的团簇化.通过比较石墨一炔到石墨五炔的储锂性能,发现并不是炔键越多其储锂性能就越好,还需考虑炔键的增多对结构稳定性的影响.在保证石墨炔类结构稳定的前提下,石墨二炔和石墨五炔达到LiC3的最大储锂量.

Graphyne, which contains planar sheets equally occupied by sp2 and sp carbon atoms, is a layered carbon allotrope. Since the length of the acetylene chains within graphyne can be variable by adjusting the number of acetylenic linkages （-C≡C-） between carbon hexagons, resulting in a family of graphyne-extended graphynes（i. e. graph-n-ynes）. In this work, density functional theory（DFT） calculations were carried out to investigate the adsorption of lithium atoms on extended graphynes monolayers, and the results were compared to extrapolate the potential relationship between lithium storage capacity and the number of acetylenic linkages. The results show that further extending the acetylenic chains might not be helpful in achie-ving higher capacity. The longer acetylene chains result in the lower carbon atom density, as well as the lower stability of the carbon networks, which should be taken into consideration seriously. High-capacity Li storage as LiC3 in graphdiyne and graph-5-yne, was achieved, and the preferred adsorption sites for Li were identified computationally. With high Li storage capacity and structural advantages, these porous carbon materials are expected to be applied in efficient lithium storage.