In-situ fabrication of Si/FeSi2@C NPs with volume control effect by fluidized bed chemical vapor deposition as anode materials

Silicon (Si) has been proven to be the most potential anode material for the next-generation lithium-ion batteries (LIBs) because of its superior theoretical capacity (∼4200 mAh g−1). However, the huge volume changes, unstable solid-state interphase (SEI) layers, and large internal stresses upon the lithiation process severely limit the practical application for commercial LIBs anodes. Herein, we fabricate the carbon-coated Si/FeSi2 nanoparticles (Si/FeSi2 @C NPs) with volume control effect by fluidized bed chemical vapor deposition (FBCVD) method to solve the above-mentioned problems. These 15 min-Si/FeSi2 @C NPs and 30 min-Si/FeSi2 @C NPs show excellent Li+ storage capacity in the first cycle (2705.9/3039.1 mAh g-1 and 2645.9/2984.2 mAh g-1) with high Initial Coulombic Efficiency (ICE) of ∼89.0% and 88.7%. In-situ TEM characterization demonstrates that the carbon coating layer and inert FeSi2 phase enable a small volume variation, only ∼37.8%, revealing the effective volume expansion control effect, and generating thin SEI layers. Besides, the perfect structure of Si/FeSi2 @C NPs makes this material a great improvement in rate performance.