The sluggish kinetics of sulfur redox reactions and the potential of polysulfide shuttling pose significant challenges to the practical application of metal–sulfur batteries (MSBs). Heterostructured materials that integrate the advantages of various components serve as ideal electrocatalysts to address these issues. This review first summarizes and analyzes the engineering strategies and the proposed working principles for heterostructures. Recent advancements in the utilizations of heterostructures in sulfur hosts, separator coating layers, and interlayers are then concluded. The material designs, preparation approaches, and the crucial roles played by heterostructures are subsequently discussed, elucidating the relationship between their structural characteristics and MSB performance. Finally, the remaining challenges are identified, and the future research directions are outlined in this promising area. This work provides invaluable insights into the development of highly efficient heterostructured electrocatalysts and the regulation of sulfur conversion processes in MSBs.

Sodium-ion batteries have garnered significant attention as a cost-effective alternative to lithium-ion batteries due to the abundance and affordability of sodium precursors. However, the lack of suitable electrode materials with both high capacity and excellent stability continues to hinder their practical viability. Herein, we couple lattice strain and sulfur deficiency effects in a tin monosulfide/reduced graphene oxide composite to enhance sodium storage performance. Experimental results and theoretical calculations reveal that the synergistic effects of lattice strain and sulfur vacancies in tin monosulfide promote rapid (de)intercalation near the surface/edge of the material, thereby enhancing its pseudocapacitive sodium storage properties. Consequently, the strained and defective tin monosulfide/reduced graphene oxide composite demonstrates a high reversible capacity of 511.82 mAh g⁻¹ at 1 A g⁻¹ and an outstanding rate capability of 450.60 mAh g⁻¹ at 3 A g⁻¹. This study offers an effective strategy for improving sodium storage performance through lattice strain and defect engineering.

Rechargeable room-temperature (RT) sodium–sulfur (Na–S) batteries hold great potential for large-scale energy storage owing to their high energy density and low cost. However, their practical application is hindered by challenges such as polysulfide shuttling and Na dendrite formation. In this study, a dual salt-based quasi-solid polymer electrolyte (DS–QSPE) was developed via in situ polymerization, achieving high ionic conductivity (4.8 × 10⁻⁴ S·cm⁻¹ at 25 °C), a high sodium-ion transference number (0.73), and effective polysulfide confinement. Theoretical calculations and experimental results indicate that the enhanced Na-ion transport is attributed to the strengthened coordination of anions with the polydioxolane chain and the increased dissociation of sodium salts. Importantly, the DS–QSPE forms an interconnected network structure in the sulfurized polyacrylonitrile (SPAN) cathode. This provides abundant and seamless electrochemical reaction interfaces that facilitate efficient and uniform ion transport pathways. As a result, the Na||SPAN battery with DS–QSPE delivers a high capacity of approximately 327.4 mAh·g⁻¹ (based on the mass of SPAN) after 200 cycles at 0.2 A·g⁻¹, retaining 81.4% of its initial capacity. This performance considerably surpasses that of batteries using liquid electrolytes. This study offers a straightforward approach to addressing the interfacial challenges in solid-state Na–S batteries.