A Novel Multielement, Multiphase, and B‐Containing SiO x Composite as a Stable Anode Material for Li‐Ion Batteries

In this study, a novel B‐containing SiO x composite is demonstrated with a remarkably improved cycling performance as a stable anode material for lithium‐ion batteries. A multielement, multiphase, B‐containing SiO x composite is successfully prepared by heating a mixture of SiO and LiBH 4 to 500 °C. The resultant product consists mainly of amorphous/nanocrystalline Si, SiO x , B, B 2 O 3 , and Li 2 SiO 3 . The in situ formed amorphous B, B 2 O 3 , and nanocrystalline Li 2 SiO 3 mostly remain at the surface of the product particles, providing a remarkable enhancement in the mechanical properties of the Si/SiO x active materials. This feature provides good accommodation for the volume change during lithiation/delithiation, consequently depressing the pulverization and fracture of the Si/SiO x active materials. As a result, the cycling stability of the prepared B‐containing SiO x composite is significantly improved. The sample prepared from SiO–0.3LiBH 4 delivers reversible capacity of 1186 mAh g −1 at 100 mA g −1 after 100 deep cycles, corresponding to the capacity retention of 81%. This outcome is more than two times higher than that of pristine SiO (33.9%).