Interface-regulated ZnO/ZnFe₂O₄composites with enhanced pseudocapacitive lithium storage

Metal–organic framework (MOF)–derived ZnFe₂O₄-based anode materials have attracted increasing interest for lithium-ion batteries (LIBs) because of their high theoretical capacity and rich multi-electron redox chemistry. However, their practical application is still severely hindered by pronounced volume variation, structural pulverization, and unstable electrode–electrolyte interfaces during repeated lithiation/delithiation processes. These issues cannot be fully mitigated by compositional optimization or morphological control alone. Herein, a polyvinylpyrrolidone (PVP)-assisted Zeolitic Imidazolate Framework-8 (ZIF-8)-derived strategy is proposed to regulate precursor evolution and interfacial architecture, enabling the rational construction of nitrogen-doped carbon-modified ZnO/ZnFe₂O₄ heterostructured anodes. The introduction of PVP during the coordination self-assembly process effectively modulates the formation of a ZnFe-MOF-like precursor and its subsequent phase evolution during thermal treatment. As a result, uniformly distributed ZnO/ZnFe₂O₄ heterostructures are successfully embedded within a conductive N-doped carbon framework, which provides effective mechanical buffering and enhanced interfacial coupling. The synergistic integration of heterostructure engineering and N-doped carbon modification significantly promotes charge transfer kinetics, stabilizes the electrode–electrolyte interface, and alleviates structural degradation during cycling. Benefiting from these structural advantages, the optimized N-C/ZnFe₂O₄/ZnO-0.3 electrode delivers a high reversible capacity of 1487 mAh g⁻¹at 0.1 A g⁻¹and maintains a stable capacity of 569.2 mAh g⁻¹after 500 cycles at 1 A g⁻¹. This work highlights the critical role of precursor regulation and interfacial engineering in MOF-derived conversion-type anodes and provides a feasible strategy for the rational design of high-performance LIB anode materials.