Engineering Si-Based Anode Materials with Homogeneous Distribution of SiO_x and Carbon for Lithium-Ion Batteries

Silicon oxide (SiO_x) is an impressive anode material for lithium-ion batteries (LIBs) because of its high specific capacity and low operating potential. Nevertheless, its large-scale commercial utilization faces the thorny problems of low conductivity and large volume expansion. The coupling of SiO_x and carbonaceous materials is a promising strategy to alleviate these shortcomings, but it is difficult to achieve a uniform distribution of SiO_x in carbon using conventional mechanical mixing and surface coating methods. Herein, we prepare homogeneous SiO_x/C nanospheres derived from triethoxyvinylsilane (VTES) by a feasible hydrothermal method and a subsequent calcination process, which is named SCDV. It has been proved that the organosilicon and the organic group in VTES can in situ convert into SiO_x units and a carbon matrix during the calcination process, which enables the uniform dispersion of SiO_x in the carbon matrix. To regulate the carbon content and improve the electrical conductivity, we further introduce 3-aminophenol and formaldehyde (RF polymer) in VTES and obtain another type of SiO_x/C nanospheres (denoted as SCVR), in which the carbon is evenly distributed on the surface of SCVR nanospheres. Benefiting from the unique structure, SCVR anodes display good structural integrity and cycling stability. Especially, at 0.2 A g^–1, SCVR shows a reversible capacity of 839 mA h g^–1 and maintains 773 mA h g^–1 after 150 cycles. At 0.5 A g^–1, it shows a specific capacity of about 590 mA h g^–1 and a capacity retention of 92% after 300 cycles. Therefore, this work proposes a good strategy to achieve the uniform distribution of SiO_x in carbon for SiO_x-based anodes, which could availably boost the application of SiO_x-based anode materials in LIBs.