The geometry structures

electronic properties and hydrogen storage properties of Si

5

and Li

2

Si

5

clusters are investigated by using the hybrid density functional theory (DFT) B3LYP method at 6.311+G(d

p) set basis level. Our results indicate that the lowest energy structure of Si

5

cluster is a three-dimensional cage

and it can not efficiently store hydrogen molecules for Si

5

cage by the same method. It will remarkably improve the hydrogen storage capacity coated by Li atoms. The Si

5

cage coated by two Li atoms (Li

2

Si

5

) can store up to 10 H

2

molecules

in which every Li atom can efficiently adsorb five H

2

molecules

corresponding to a maximum mass fraction of 11.554% with an average adsorption energies of 7.259~11.330 kJ/mol per H

2

molecule. The results demonstrate that Li decorated Si

5

cage can serve as an ideal hydrogen storage material under ambient conditions.