Oxygen containing Si–H nanoparticles: a potential electrode for Li–ion battery

Abstract

Using density functional theory based computations; the role of vacancy and defects in hydrogen terminated silicon nano particles (NP) in the lithium intercalation process is investigated. The study shows that Li cannot bind to the NPs without vacancy or defects. The presence of a single dangling bond or defects such as O or OH radical substituting H, induces interaction between Li atoms and NPs. The Si–Si coordination number reduces with increasing Li intake however, total average coordination of Si increases beyond 5. Presence of H, O and OH is seen to be conducive for the intercalation process. The average electrode potential with respect to Li/Li+ is seen to vary between 2.4 and 0.05 V over NPs with various defects. It is observed that one of the stable electrode material can be Si10H8O4 NPs. Electronic structure calculations of the intercalation of up to13 Li in Si10H8O4 NPs was carried out. It corresponds to a specific capacity of 988 mAh g−1 for these NPs. The results can be extrapolated for higher intake, making this material a potential anode. The stability analysis shows that Si:H NPs containing oxygen are stable and are promising material for anode in lithium battery under deep discharge.