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

Abstract

Silicon oxide (SiOx) 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 SiOx and carbonaceous materials is a promising strategy to alleviate these shortcomings, but it is difficult to achieve a uniform distribution of SiOx in carbon using conventional mechanical mixing and surface coating methods. Herein, we prepare homogeneous SiOx/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 SiOx units and a carbon matrix during the calcination process, which enables the uniform dispersion of SiOx 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 SiOx/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 SiOx in carbon for SiOx-based anodes, which could availably boost the application of SiOx-based anode materials in LIBs.