Hollow Mesoporous SiO2/C Nanospheres: Toward Advanced Anode Materials for High-Performance LIBs

Silicon dioxide (SiO2) has a much lower volume expansion rate than monolithic silicon when used as an anode in lithium-ion batteries, and due to its high theoretical capacity and more balanced electrochemical properties, it has attracted the attention of a wide range of researchers. However, the inherent low electrical conductivity of SiO2 and the expansion problem during cycling are still the key issues limiting its practical application. This work utilizes a low-cost, easy step-by-step synthesis method to prepare SiO2/C hollow structure nanospheres (DCSF) by using tetrapropoxysilane as the silicon source and phenolic resin as the carbon source. The structure and size of DCSF were also regulated by controlling the time difference between the polymerization and hydrolysis reactions in the room temperature. The disordered carbon encapsulated in the outer layer and the special hollow mesoporous structure of DCSF with an appropriate C:SiO2 ratio not only provides more migration channels and accelerated migration kinetics for lithium ions and electrons but also maintains the stability of the electrode structure by alleviating the volume expansion of SiO2 during the cycling process. Due to the synergistic effect of structure and chemical composition, the DCSF exhibits excellent electrochemical properties including excellent multiplicative rate, high efficiency (at 1245.07 mA h g–1 at 0.1 A g–1 and 515.67 mA h g–1 at 5 A g–1) and long-term cycle life (456.61 mA h g–1 after 600 cycles at 10 A g–1). This work has the potential to provide an efficient solution for the design of SiO2/C for high-energy lithium battery energy storage.