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

Abstract

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 few-atomic-layer Si on nanoporous carbon. 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. 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.

Keywords: Silicon anodes, Lithium batteries, Composites, Nanoengineering