Preparation and Performance Study of Core-Shell Structured SiO2@C Anode Materials with ZIF-8 and PVP As Carbon Sources

Abstract

At room temperature in aqueous solution, SiO₂ particles modified with PVP on the surface were simultaneously added to the ZIF-8 raw material. Utilizing the adsorption effect of PVP on ZIF-8, ZIF-8 rapidly formed on the surface of SiO₂, creating a complete coating layer. TEM and XPS results confirmed that the coating structure remained intact after calcination, and the thickness of the amorphous carbon coating layer was 35–55 nm. The obtained SiO₂@C anode material exhibited excellent electrochemical performance. The first discharge specific capacities of 10% SiO₂@C and 20% SiO₂@C were 579.4 and 833.1 mA h/g, respectively, and the first efficiencies were 76.4 and 72.2%, respectively. The material also demonstrated excellent high-rate charge and discharge performance. At a current density of 1.2 A/g, the discharge specific capacities of 10% SiO₂@C and 20% SiO₂@C were 270 and 365 mA h/g, respectively. When the current density was restored to a low value, the discharge specific capacities could almost fully recover. The carbon layer formed by ZIF-8 and PVP gave the material good cycling performance. After 240 cycles, the charge specific capacities of 10%SiO₂@C and 20%SiO₂@C were still 438.7 and 495.8 mA h/g, respectively.