Hollow silica spheres with facile carbon modification as an anode material for lithium-ion batteries

Hollow silica (H-SiO₂) spheres are prepared via a self-assembly approach without sacrificial templates. To address the poor electrical conductivity and mechanical stability problems of H-SiO₂, carbon coating is adopted to modify the H-SiO₂ spheres through a facile solution-mixing method. In the obtained micron-level H-SiO₂/C composite, the carbon coating layer can act as a mechanical support layer to maintain the structure stability of the H-SiO₂ spheres, while the inner hollow space can accommodate the volume expansion during cycling. Moreover, the N-doped carbon can provide a fast electron transfer channel for the H-SiO₂/C electrode during lithiation/delithiation process, helping the electrode exhibiting significantly improved cycling and rate performance. The reversible capacity of the H-SiO₂/C electrode after 400 cycles is 564.0 mA h g⁻¹ at a current density of 200 mA g⁻¹, with a capacity retention of 88.3% as against the first cycle. The electrode delivers a reversible capacity of 423.1 mA h g⁻¹, 280.8 mA h g⁻¹ and 190.3 mA h g⁻¹ at the current density of 1 A g⁻¹, 3 A g⁻¹ and 5 A g⁻¹, respectively. This work provides a facile strategy for the large-scale production of H-SiO₂/C anode materials for LIBs.