Peng Huang, Ying Wang, Wei Ai
Developing high-performance FeS2-based anodes for sodium-ion batteries is impeded by sluggish kinetics, poor conductivity, and severe volume variation. Herein, we report a rationally designed FeS2/SnS2/rGO composite featuring a three-dimensional hierarchical heterostructure. In this architecture, SnS2 nanosheets are uniformly anchored on reduced graphene oxide framework, while FeS2 nanoparticles are dispersed throughout the scaffold, forming interconnected electron pathways and structural robustness. More importantly, the abundant FeS2-SnS2 heterointerfaces induce built-in electric fields that regulate charge redistribution and accelerate interfacial reaction kinetics, thereby promoting surface-dominated pseudocapacitive behavior and rapid Na+ diffusion. As a result, the FeS2/SnS2/rGO electrode delivers a high reversible capacity of 618 mAh g-1 at 0.1 A g-1 and retains 500 mAh g-1 at 5 A g-1, together with outstanding cycling stability (536 mAh g-1 after 400 cycles at 2 A g-1 with 99.5% retention). Furthermore, full cells paired with NaNi1/3Fe1/3Mn1/3O2 exhibit good rate capability and long-term stability. This work demonstrates that heterointerface-induced electric-field regulation is an effective strategy for accelerating reaction kinetics in conversion-type anodes.