Enhancing the kinetics and stability via interface riveting and spatial confinement of bimetallic iron tin sulfides for high-rate and long-cycling sodium storage

Abstract

Enhancing the reaction kinetics and structural stability in metal sulfide-based anodes through heterostructure construction coupled with carbon modification is a highly effective approach for improving sodium storage performance. However, the potential benefits associated with heterogeneous structures are often compromised due to the limited and poor interfacial contact among randomly distributed metal sulfides, as well as inadequate protection of active materials by the carbon matrix. To address these challenges, we delicately design and synthesize FeS₂/SnS₂ nanoparticles embedded within multi-channel carbon nanofibers (P-FeS₂/SnS₂@MC) via a sequential hydrothermal, electrospinning and calcination processes. Unlike conventional metal salts, the use of FeSn Prussian blue analogues (FeSn PBAs) as a functional precursor, plays a critical role in establishing multiphase interface riveting of bimetallic sulfides with rich heterointerfaces and strong interactions, thereby enhancing reaction kinetics and structural stability. Moreover, the incorporation of multi-channel carbon nanofibers guarantees rapid ion/electron transfer kinetics, favorable spatial confinement, and effective volume variation buffering. As expected, attributing to the synergistic effects, the P-FeS₂/SnS₂@MC demonstrates a high reversible capacity of 672 mAh g⁻¹ at 1 A g⁻¹, excellent rate capability of 571 mAh g⁻¹ at 5 A g⁻¹, and outstanding long-cycling stability with 87 % retention at 5 A g⁻¹ over 2000 cycles. This study highlights the significance of interface engineering and spatial confinement in advancing metal sulfide-based anodes for high-performance energy storage.