Interface-Engineered Nickel Foam Electrodes with Polydopamine and Ultraphene for High-Performance Nickel Iron Metal–Organic Framework Hybrid Energy Storage

High Resolution Image Download MS PowerPoint Slide Nickel foam (NF) has been widely employed as a conductive scaffold for electrochemical energy storage, owing to its high electrical conductivity, mechanical robustness, and three-dimensional porous architecture that facilitates rapid charge transport and electrolyte penetration. However, the intrinsically inert surface of NF limits active material adhesion and uniform growth. In this work, a hierarchical interfacial engineering strategy is proposed on modifying NF by sequentially coating with polydopamine (PDA), anchoring Ultraphene nanosheets, and subsequently growing nickel iron metal–organic frameworks (NiFeMOF) for the application on high-performance electrodes of battery-supercapacitor hybrids (BSHs). Optimizing the PDA polymerization time offers uniform surface coverage and abundant functional groups, while introducing Ultraphene layers provides improved conductivity and ion accessibility. Building upon this engineered interlayer, the NiFeMOF-coated modified NF (U-PDA-NF) delivers a significantly higher specific capacitance of 1911 mF/cm 2 at 6 mA/cm 2 than that of NiFeMOF/NF, attributed to enhanced nucleation, reduced resistance, and favorable surface-controlled kinetics. The assembled BSH achieves a maximum energy density of 26.9 mWh/cm 2 at 325 mW/cm 2, and excellent cycling stability with a capacitance retention of 93.2% and Coulombic efficiency of 96.9% after 10,000 cycles. This study demonstrates effectiveness of PDA/Ultraphene interlayers in unlocking full potentials of NF substrates for advanced hybrid energy storage applications. This work introduces a versatile and scalable surface modification route that can be extended to various metal foam substrates and active materials, providing a general strategy for improving interfacial compatibility and electrochemical efficiency. The demonstrated interlayer design highlights a direction for constructing high-performance hybrid energy storage systems that bridge the gap between supercapacitors and batteries.