Electronic structure of LiSi

Silicon is of special interest in lithium-ion batteries (LIBs) since it has large theoretical specific capacity or volumetric capacity. The crystal structure, charge distribution and density of states of LiSi as the Li-poorest side compound at the start of Li intercalation mechanism for Si anode in LIBs has been studied by using Density Functional Theory calculations. The triangular pyramids are formed by four Li atoms. Compared with the charge density of crystalline Si, the Si-Si covalent bonds in LiSi become weak due to Li intercalation. On the other hand, the electrons around the Li atoms in LiSi increase compared with metallic Li. The Li atoms in LiSi have negative charge of 0.830～0.843 compared with metallic Li. These electrons, which are transferred from p electrons in the Si atoms, are mainly made of p electrons of the Li atoms. When considering the lithium intercalation reaction from crystalline Si to LiSi, the average intercalation voltage is 0.4053 V