In Situ Synthesis of Graphene‐Coated Silicon Monoxide Anodes from Coal‐Derived Humic Acid for High‐Performance Lithium‐Ion Batteries

Abstract Silicon monoxide (SiO) is attaining extensive interest amongst silicon‐based materials due to its high capacity and long cycle life; however, its low intrinsic electrical conductivity and poor coulombic efficiency strictly limit its commercial applications. Here low‐cost coal‐derived humic acid is used as a feedstock to synthesize in situ graphene‐coated disproportionated SiO (D‐SiO@G) anode with a facile method. HR‐TEM and XRD confirm the well‐coated graphene layers on a SiO surface. Scanning transmission X‐ray microscopy and X‐ray absorption near‐edge structure spectra analysis indicate that the graphene coating effectively hinders the side‐reactions between the electrolyte and SiO particles. As a result, the D‐SiO@G anode presents an initial discharge capacity of 1937.6 mAh g −1 at 0.1 A g −1 and an initial coulombic efficiency of 78.2%. High reversible capacity (1023 mAh g −1 at 2.0 A g −1 ), excellent cycling performance (72.4% capacity retention after 500 cycles at 2.0 A g −1 ), and rate capability (774 mAh g −1 at 5 A g −1 ) results are substantial. Full coin cells assembled with LiFePO 4 electrodes and D‐SiO@G electrodes display impressive rate performance. These results indicate promising potential for practical use in high‐performance lithium‐ion batteries.