Interfacial Electric‐Field Nanoarchitectonics of a 3D FeS ₂ /SnS ₂ /rGO Heterostructure for Fast Sodium Storage

Developing high‐performance FeS 2 ‐based anodes for sodium‐ion batteries is impeded by sluggish kinetics, poor conductivity, and severe volume variation. Herein, we report a rationally designed FeS 2 /SnS 2 /rGO composite featuring a three‐dimensional hierarchical heterostructure. In this architecture, SnS 2 nanosheets are uniformly anchored on reduced graphene oxide framework, while FeS 2 nanoparticles are dispersed throughout the scaffold, forming interconnected electron pathways and structural robustness. More importantly, the abundant FeS 2 ‐SnS 2 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 FeS 2 /SnS 2 /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 NaNi 1/3 Fe 1/3 Mn 1/3 O 2 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.