Sulfur-induced abundant oxygen vacancies in hollow silica microsphere toward super anode

Abstract

• The sulfur-induced strategy is developed to generate abundant oxygen vacancies. • The oxygen vacancy concentration increases by 65% compared with blank smaples. • The SHSiO 2-x /G shows the highest capacity among reported silicon oxides anodes. • The SHSiO 2-x /G shows excellent stability (~1200 mA h g −1 after 4000 cycles at 3 A/g). • The enhanced mechanisms are explored by DFT and experimental analysis. Introduction of oxygen vacancies would greatly improve the comprehensive lithium-ion (Li + ) storage performance. Herein, the facile and efficient sulfur-induced strategy is developed firstly to generate abundant oxygen vacancies into the hollow porous SiO 2 (SHSiO 2-x ). Compared with the method without adding sulfur, the oxygen vacancy concentration increases by 65%. Then, the obtained SHSiO 2-x is further embedded in the three-dimensional (3D) graphene scaffold to obtain the SHSiO 2-x /G anode. Due to the greatly improved oxygen vacancy concentration, the anode shows the highest specific capacity at various current densities (such as ~2500 mA h g −1 at 0.2 A/g) among reported silicon oxides anodes and presents outstanding cycling stability (~1200 mA h g −1 after 4000 cycles at 3 A/g). Based on the density functional theory (DFT) and experimental analysis, the advantages of abundant oxygen vacancies on improving Li + storage performance are studied. Additionally, the hollow porous microstructure of SHSiO 2-x and 3D graphene scaffold would further improve the Li + / electrons transfer and hinder the volume expansion. The distinct method for the introduction of abundant oxygen vacancies and the structural design pave a new avenue towards high-performance oxides anodes.