Micron-Sized Nanostructured Si–C Composites for High-Performance Li-Ion Battery Anodes

Silicon–carbon composite materials offer an attractive and realistic pathway to lithium-ion batteries with higher energy density. Here, a scalable chemical vapor deposition (CVD) process is used to form micron-sized Si–C composites with uniform few-atomic-layer Si on nanoporous carbon. We find that the optimal deposition temperatures are 450–525 °C. The ultrathin Si layer successfully releases stress in the micron-sized particles, while the small pores eliminate the formation of excessive amounts of solid electrolyte interphase, as validated by elemental mapping. Therefore, the resulting Si–C composites demonstrate a high specific capacity exceeding 1400 mAh/g, stable cycling with a decay rate of <5%/100 cycles in the half cell, an initial Coulombic efficiency of 85.2%, and excellent rate capabilities such as 84% retention at 4C. Moreover, the material demonstrates excellent air and water stability, allowing for similar electrode casting and preparation methods as graphite. The corresponding LiNi0.92Mn0.02Co0.06O2/Si–C full cells show stable cycling with 84% capacity retention over 200 cycles, which is attractive for high-energy-density lithium-ion batteries and compares favorably to other silicon-based anodes in terms of both performance and scalability.