A first-principles study on the effect of oxygen content on the structural and electronic properties of silicon suboxide as anode material for Lithium Ion Batteries

摘要

Silicon suboxide is currently considered as a unique candidate for lithiumion batteries anode materials due to its considerable capacity. However, noadequate information exist about the role of oxygen content on its performance.To this aim, we used density functional theory to create silicon suboxidematrices of various Si:O ratios and investigated the role of oxygen content onthe structural, dynamic, electronic properties and lithiation behavior of thematrices. Our study demonstrates that the O atoms interact strongly with theinserted Li atoms resulting in a disintegration of the host matrix. We foundthat higher concentration of oxygen atoms in the mixture reduces its relativeexpansion upon lithiation, which is a desirable quality for anode materials. Ithelps in preventing crack formation and pulverization due to large fluctuationsin volume. Our study also demonstrate that a higher oxygen content increasesthe lithium storage capacity of the anode. However, it can also cause theformation of stable complexes like lithium silicates that might result intoreversible capacity loss as indicated by the voltage-composition curves. Thestudy provides valuable insights into the role of oxygen in moderating theinteraction of lithium in silicon suboxide mixture in microscopic details.