Improving the conductivity of silicon anode and the stability of solid electrolyte interface by Si/Bi2S3 nanocomposite

Abstract

In the field of lithium battery research, silicon has received extensive attention due to its high specific capacity and abundant reserves, but the factors such as large volume expansion and low electrical conductivity limit its further development. In this work, Si/Bi2S3 composites with a heterogeneous structure is obtained by using a hydrothermal reaction. The heterogeneous structure can promote the rapid transfer of charge, and the interfacial coupling effect of the heterogeneous structure has an adsorption effect on Li2S generated by the conversion reaction of Bi2S3, and Li2S is distributed on the surface of the Si/Bi2S3 composite to become an effective component of solid electrolyte interface (SEI), promoting the stability of the SEI film. The Bi and LixBi (x = 1, 3) produced during the conversion and alloying reactions of Bi2S3 can reduce the internal resistance of the Si/Bi2S3 composite. Thus, at a current density of 500 mA g−1, the initial charge-discharge specific capacity of Si/Bi2S3 is 2240.5/2767.8 mAh g−1. After 200 cycles, the discharge specific capacity can achieve 1443.3 mAh g−1, with a capacity retention of 52.1 %.