Core‐Shell‐Structured SiO x —C Composite for Lithium‐Ion Battery Anodes

A simple method to synthesize a uniform composite material consisting of wet‐milled SiO x core and carbon shell is studied. This SiO x —C core‐shell composite is then used as anode materials for lithium‐ion batteries, with wet‐milled SiO x and raw SiO x anodes used for comparison. It is found that the batteries fabricated with wet‐milled SiO x —C composite show the best cyclic performance and excellent rate capability compared with wet‐milled SiO x and raw SiO x . This approach is beneficial because of the reduced size of wet‐milled SiO x powders. The coating of carbon shell is effective in improving the conductivity of SiO x and diminishing the volume effect during lithiation/delithiation processes. Moreover, the Li 2 O and Li 4 SiO 4 generated in the first cycle further suppress the volume effects. Under the galvanostatic mode with charging and discharging current density of 0.1 Ag −1 , the wet‐milled SiO x —C composite electrode delivers an initial reversible capacity of 1279 mAh g −1 , with a capacity retention as high as 97.3% (1244 mAh g −1 ) even after 170 cycles and coulombic efficiency as high as 99.8%. This approach is simple and has great potential for the large‐scale production of high‐performance SiO x ‐based anode materials.