Investigation of the irreversible reaction mechanism and the reactive trigger on SiO anode material for lithium-ion battery

Abstract

To clarify the reaction mechanism of SiO anode, the chemical and the electrochemical reactions of SiO and SiO2 with Li-metal and first principles calculations were investigated. In the chemical reactions, SiO and amorphous SiO2 formed lithium silicide (Li44Si5) and lithium silicate (Li2SiO3, Li4SiO4) by reacting with Li. In the electrochemical reactions, crystalline SiO2 did not react with Li though amorphous SiO2 did do so. These results indicated that both Si area and amorphous SiO2 area in SiO matrix play an important part in SiO charge–discharge process. This suggests that the dangling-bond in amorphous SiO2 can react with Li easily. This finding was also confirmed by first principles calculations using VASP code.