Silica quantum dots coupled with N-dopping carbon achieving zero-strain and high-performance Li+ storage

Si anodes suffer from huge volume expansion and sluggish reaction kinetics. Herein, SiO2 quantum dots (size below 20 nm) coupled with the carbon framework (SiO2 QD/NC) have been successfully synthesized. Due to the size effect, the SiO2 QD/NC demonstrates a minimal volume strain of 0.3 %, highlighting its zero-strain feature. Moreover, the prepared SiO2 QD/NC material offers abundant active sites and shortens lithium-ion (Li+) diffusion distance. The strong coupling effect between SiO2 QD and carbon framework realized by forming Si-C bonds further enhances the reaction kinetics and structural stability. After 200 cycles, it exhibits a capacity retention of around 90 %, indicating excellent structural stability. Furthermore, the specific capacity of SiO2 QD/ NC is above twice that of SiO2 nanoparticles anchored carbon framework (SiO2 NP/NC). This unique structure effectively mitigates the volume expansion of SiO2 and increases active sites, thereby contributing to the development of Si-based anodes with high specific capacity and long-term stability.