Interface Engineering of Silicon/Carbon Thin-Film Anodes for High-Rate Lithium-Ion Batteries

Silicon is one of the most promising alternative active materials for next-generation lithium-ion battery (LIB) applications due to its advantage of high specific capacity. However, the enormous volume variations during lithiation/delithiation still remain to be an obstacle to commercialization. In this work, binder-free pure silicon and silicon/carbon (Si/C) multilayer thin-film electrodes, prepared by scalable one-step magnetron sputtering, are systematically investigated by an interlayer strategy. Herein, we present a rationally structural modification by an amorphous carbon film to enhance the electrical conductivity, mechanical integrity, and electrochemical performance of Si film-based LIBs. Therefore, to maintain the consistency of the direct-contact layer with the electrolyte and current collection, symmetrical Si/C/Si and Si/C/Si/C/Si/C/Si electrodes are deliberately designed to study the influence of embedded carbon. An anode with a carbon content of 10.38 wt % yields an initial discharge specific capacity of 1888.74 mAh g-1 and a capacity retention of 96.82% (1243.56 mAh g-1) after 150 cycles at a high current density of 4000 mA g-1. It also shows that the best rate capability remains 96.0% of the initial capacity in the 70th cycle. At last, three mechanisms are proposed for an in-depth understanding of the interface effect. This work offers a new perspective scheme toward Si/C-based LIBs with a capability of high rate and high energy density.