Ni-Catalyzed Preparation of Si/C Composites Encapsulated in a Carbon Layer and Their Superior Lithium Storage Capabilities

Abstract

In the preparation of silicon/starch-derived carbon (Si/C) composites, Ni(NO₃)₂·6H₂O serves as the precursor for the in situ synthesis of the metallic Ni catalyst, which can effectively catalyze the reaction between Si and C to produce SiC. Moreover, metallic Ni also undergoes alloying reaction with Si, yielding the fibrous Ni₂Si phase. These components endow the inert matrix in composites with high mechanical strength, so the obtained Ni–Si/C composites exhibit superior electrochemical performances than pure Si/C composites. On this basis, a carbon-coating layer constructed by toluene chemical vapor deposition further improves the conductivity of the inert matrix and structural integrity of composites during cycling. Therefore, the as-prepared Ni–Si/C@C composites exhibit superior Li⁺ storage performances compared to Si/C and Ni–Si/C composites. Their specific capacities at 0.2, 0.3, 0.5, 1.0, 2.0, and 3.0 A·g^–1 are 1001, 979, 929, 853, 725, and 640 mA h·g^–1, respectively, and capacity retention after 950 cycles at 1.0 A·g^–1 reaches 77.1%.