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

TL;DR

This study uses density functional theory to analyze how varying oxygen content in silicon suboxide affects its structural, electronic, and lithiation properties, revealing implications for lithium-ion battery anode performance.

Contribution

It provides detailed insights into how oxygen content influences silicon suboxide's behavior and capacity as an anode material, a topic previously lacking comprehensive understanding.

Findings

Higher oxygen reduces matrix expansion during lithiation

Increased oxygen enhances lithium storage capacity

Oxygen promotes formation of stable lithium silicates

Abstract

Silicon suboxide is currently considered as a unique candidate for lithium ion batteries anode materials due to its considerable capacity. However, no adequate information exist about the role of oxygen content on its performance. To this aim, we used density functional theory to create silicon suboxide matrices of various Si:O ratios and investigated the role of oxygen content on the structural, dynamic, electronic properties and lithiation behavior of the matrices. Our study demonstrates that the O atoms interact strongly with the inserted Li atoms resulting in a disintegration of the host matrix. We found that higher concentration of oxygen atoms in the mixture reduces its relative expansion upon lithiation, which is a desirable quality for anode materials. It helps in preventing crack formation and pulverization due to large fluctuations in volume. Our study also demonstrate that a higher oxygen content increases the lithium storage capacity of the anode. However, it can also cause the formation of stable complexes like lithium silicates that might result into reversible capacity loss as indicated by the voltage-composition curves. The study provides valuable insights into the role of oxygen in moderating the interaction of lithium in silicon suboxide mixture in microscopic details.