SiO x C y Microspheres with Homogeneous Atom Distribution for a High-Performance Li-Ion Battery.

The broad application of silicon-based materials is limited by large volume fluctuation, high preparation costs, and complicated preparation processes. Here, we synthesized SiO x C y microspheres on 3D copper foams by a simple chemical vapor deposition method using a low-cost silane coupling agent (KH560) as precursors. The SiO x C y microspheres are available with a large mass loading (>3 mg/cm 2 ) on collectors and can be directly used as the electrode without any binders or extra conductive agents. As a result, the as-prepared SiO x C y shows a high reversible capacity of ∼1240 mAh g -1 and can be cycled more than 1900 times without decay. Ex situ characterizations show that the volume change of the microspheres is only 55% and the spherical morphology as well as the 3D structure remain intact after cycles. Full-cell electrochemical tests paired with LiFePO 4 as cathodes show 87% capacity retention after 500 cycles, better than most reported results, thus showing the commercial potential of the material.