Design of Janus Heterostructures Embedded in Carbon Nanofibers via Heterointerface and Structural Engineering for Rapid Polysulfide Conversion

Abstract

The sluggish redox kinetics of sulfur electrode and the “shuttle effect” caused by soluble lithium polysulfides (LiPS) are critical challenges in the advancement of high-energy lithium-sulfur batteries. Here, a pioneering flexible self-supporting composite scaffold that incorporates Janus V2O3/VN heterostructures embedded within multichannel nitrogen-doped carbon nanofibers (MNCNF) is introduced. The MNCNF features a 3D hierarchical porous conductive network that facilitates rapid ion/electron transport while offering substantial space for high sulfur loading. Theoretical calculations demonstrate that the Janus V2O3/VN heterocatalyst, featuring a built-in interfacial electric field, facilitates a smooth and rapid “capture-diffusion-conversion” of LiPS by leveraging the V2O3’s strong adsorption capacity, VN's high catalytic capability and promoted interfacial charge/ion transport, thereby accelerating bi-directional sulfur conversion. The as-designed sulfur electrode with a sulfur loading of 2.0 mg cm−2 showcases high rate capability of 618 mAh g⁻¹ at 5C with 68.1% capacity retention over 500 cycles. Notably, under harsh conditions of high sulfur loading (6.0 mg cm−2) and lean electrolyte (7.5 µL mg−1), it achieves a high initial areal capacity of 4.92 mAh cm−2 with 94.8% capacity retention over 150 cycles. This work offers valuable insights for the rational design of optimal vanadium-based heterocatalysts aimed at facilitating rapid sulfur redox conversion.