Boost the cyclability and Na+ diffusion kinetics of Sb2S3 anode by CNTs cross-linking N-doped carbon matrix

Abstract

Antimony sulfides exhibit a tremendous potential owing to the high theoretical specific capacity from multiple redox storage mechanisms for sodium-ion batteries (SIBs). However, these bottlenecks, including low electrical conductivity, poor ionic diffusion kinetics, and severe volume expansion, still restrict the development of antimony sulfide as SIBs anodes. Meanwhile, in view of long-term interests and practical application, the cost-efficient preparation methods become an imminent challenge to the advancement of high-performance SIBs anodes. Here, a novel three-step strategy, composed of co-precipitation, heat reduction processes, and sulfation conversion, was utilized to construct a “reinforced concrete” architecture, in which Sb2S3 nanoparticles embedded in N-doped carbon matrix (NC) modified by carbon nanotubes (CNTs), denoted as Sb2S3/CNTs/NC. As the “cement block”, the N-doped 3D carbon matrix can promote the electron migration and reduce the aggregation of active materials upon cycling. In terms of “rebars” (i.e., 1D CNTs) for ensuring the anode integrality during incessant sodiation/de-sodiation processes, they function as binders and stabilizers, which intimately cross-link with Sb2S3 nanoparticles and carbon matrix, accommodate the volume change, and maintain the fast transfer of electron transfer inside the whole composite. Benefiting from these merits of the hierarchical structure (i.e., 3D NC and 1D CNTs), as an anode for SIBs, Sb2S3/CNTs/NC demonstrates an improved sodium storage capability with an initial specific capacity of 770.80 mAh g−1 at 0.1 A g−1 and a superior initial coulombic efficiency (ICE) of 79.90%. Moreover, even at a high current density of 1.0 A g−1, a reversible capacity of 313.54 mAh g−1 can be delivered after 350 long cycles, indicating the stable cyclicity. The Sb2S3/CNTs/NC with designed construction and enhanced electrochemical performance could provide a new perspective on low-cost, time-saving, and exercisable synthesis approach for high-performance sulfide-based anodes.