Engineering Si-Based Anode Materials with Homogeneous\nDistribution of SiO_<i>x</i> and Carbon for Lithium-Ion\nBatteries

Abstract

Silicon\noxide (SiO_<i>x</i>) is an impressive\nanode material for lithium-ion batteries (LIBs) because of its high\nspecific capacity and low operating potential. Nevertheless, its large-scale\ncommercial utilization faces the thorny problems of low conductivity\nand large volume expansion. The coupling of SiO_<i>x</i> and carbonaceous materials is a promising strategy to alleviate\nthese shortcomings, but it is difficult to achieve a uniform distribution\nof SiO_<i>x</i> in carbon using conventional mechanical\nmixing and surface coating methods. Herein, we prepare homogeneous\nSiO_<i>x</i>/C nanospheres derived from triethoxyvinylsilane\n(VTES) by a feasible hydrothermal method and a subsequent calcination\nprocess, which is named SCDV. It has been proved that the organosilicon\nand the organic group in VTES can in situ convert into SiO_<i>x</i> units and a carbon matrix during the calcination\nprocess, which enables the uniform dispersion of SiO_<i>x</i> in the carbon matrix. To regulate the carbon content and improve\nthe electrical conductivity, we further introduce 3-aminophenol and\nformaldehyde (RF polymer) in VTES and obtain another type of SiO_<i>x</i>/C nanospheres (denoted as SCVR), in which\nthe carbon is evenly distributed on the surface of SCVR nanospheres.\nBenefiting from the unique structure, SCVR anodes display good structural\nintegrity 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\n0.5 A g^–1, it shows a specific capacity of about\n590 mA h g^–1 and a capacity retention of 92% after\n300 cycles. Therefore, this work proposes a good strategy to achieve\nthe uniform distribution of SiO_<i>x</i> in carbon\nfor SiO_<i>x</i>-based anodes, which could availably\nboost the application of SiO_<i>x</i>-based anode\nmaterials in LIBs.