Synergistically Designed Carbon‐Free MoS2/MoO2 Heterostructure Anodes with Interfacial Covalent Bonds for High‐Rate Sodium‐Ion Batteries

Abstract The development of hierarchical heterostructured materials for sodium‐ion batteries (SIBs) remains hindered by suboptimal high‐rate cycling performance, primarily due to phase interface pulverization and separation during charge–discharge processes. To address these challenges, we designed a carbon‐free hierarchical structure comprising few‐layered MoS₂ nanosheets and MoO₂ nanocrystals through precise compositional optimization and rational structural engineering. The heterogeneous components are interconnected through robust S─O covalent bonds, which theoretical calculations and experimental results confirm generate a built‐in electric field at the heterointerfaces, significantly enhancing reaction kinetics. Crucially, these covalent bonds stabilize the heterointerfaces, improving structural integrity and mitigating electrode material agglomeration and pulverization. Additionally, the MoS₂/MoO₂ heterostructure enhances Na⁺ adsorption energetics and reduces Na⁺ diffusion barriers, facilitating efficient ion transport. Leveraging its abundant heterointerfaces and stable architecture, the composite delivers exceptional rate performance (432.7 mAh·g⁻¹ at 10 A·g⁻¹) and outstanding cycling stability (nearly 100% capacity retention over 400 cycles at 5 A·g⁻¹). This work provides a strategic framework for designing heterostructured materials with stable interface‐rich architectures, advancing the development of high‐performance conversion/alloy‐type anodes for energy storage applications.