Construction of MoO2 Ultra-uniformly Coated FeS2 with Tailored Interfacial Traits toward Improved Energy Storage

Abstract

Iron disulfide (FeS2), a low-cost material, displays considerable theoretical specific capacity (894 mA h g–1) but still suffers from shuttling of polysulfides and sluggish kinetics. The MoO2 electrocatalyst has been successfully applied in Li–S systems, bringing about fascinated electrochemical improvements. Herein, through the gasification coating manners, the ultra-uniform distribution of MoO2 with abundant catalytic sites is surprisingly obtained, incorporating with the establishment of interfacial Fe–O–Mo bonds. Benefiting from the unique structural traits, optimized FeS2@MoO2 delivers an initial discharge capacity of 1271 mA h g–1. In addition, after 100 cycles, the capacity of FeS2@MoO2 could reach ∼308 mA h g–1, larger than that of pristine FeS2. Supported by the kinetic analysis, it could be found that the existing Fe–O–Mo bonds contribute to enhanced ion/e– diffusion behaviors during the intercalation/deintercalation process, ultimately resulting in outstanding lithium-ion storage capacity. Moreover, benefitting from the detailed resistance analysis and the galvanostatic intermittent titration technique test, the existence of MoO2 and Fe–O–Mo interfacial bonds could facilitate the diffusion of ions/electrons transferring and structural stability. Thus, this work is expected to provide insights into the construction of MoO2 ultra-uniformly coated FeS2 with tailored interfacial traits in energy storage systems.