Quantitatively Tunable Anionic Vacancies of Iron Disulfide Nanorods with Superior Cyclability and Rate Capability for Li-Ion Batteries

Introducing the defects into transition metal sulfides is a common strategy to improve efficiency of electrochemical reaction. The effect of vacancy concentration on the performance is also vital, but it is rarely paid attention. Herein, sulfur vacancies with quantitative concentration were introduced into porous FeS2 nanorods as anode materials for lithium-ion batteries (LIBs). After optimizing the sulfur vacancy concentration, the VS-FeS1.71/C nanorod electrode delivered good rate performance (763.1 mA h g–1 at 5.0 A g–1) and long cyclic performance (517.8 mA h g–1 after 1200 cycles at 5.0 A g–1). This superior lithium storage performance was ascribed to moderate sulfur vacancies into the FeS2 crystal lattice, which rearranged local atoms, regulated the electronic structure, promoted electronic conductivity, and afforded increasing active adsorption sites for Li+. However, excessive sulfur vacancies resulted in deformation of crystal planes and structural damage, which astricted the diffusion rate of Li+. The experimental results indicate that the strategy of optimizing defect concentration is beneficial to promote the electrochemical reaction, providing a feasible way to improve the performance of LIBs.