Synergistic regulation of ionic confinement and heterointerfaces in porous nanofloral nickel oxide/nickel ferrite layer for stable Zn anodes in aqueous zinc-ion batteries.

Aqueous zinc-ion batteries (AZIBs) are regarded as competitive candidates for low-cost stationary energy storage, yet the unstable Zn anode/electrolyte colloidal interface severely deteriorates their cycling lifespan. Addressing this, a porous nanofloral nickel oxide/nickel ferrite (NiO/NiFe2O4, denoted as NiO/NFO) heterostructured layer is constructed via a colloidal self-assembly-assisted hydrothermal-calcination route, serving as an artificial interface to modulate interfacial Zn2+ transport and stabilize the colloidal contact between Zn and electrolyte. The NiO/NFO heterostructure exhibits dual structural merits: (i) The spinel NFO phase provides Ni2+/Fe3+ active sites to strengthen Zn2+ adsorption (binding energy: -0.82 eV for NFO-Zn2+ vs. -0.31 eV for NiO-Zn2+), reducing nucleation overpotential to 27.9 mV; (ii) The interconnected nanofloral pores facilitate electrolyte infiltration and accelerate Zn2+ diffusion. More importantly, the 2.96-2.99 Å nanopores in NiO/NFO act as "nanosieves" to induce ionic confinement: they promote desolvation of [Zn(H2O)6]2+ (diameter: 8.6 Å) while blocking H2O molecules, thus suppressing HER and by-product (Zn(OH)2) formation. Symmetric cells with NiO/NFO-Zn anodes cycle stably for 210 days at 0.1 mA cm-2 and maintain 660 h/220 h cycling at 1/5 mA cm-2. Full cells (NiO/NFO-Zn//NH4V4O10) deliver a reversible capacity of 189 mAh g-1 at 1 A g-1, retain 117.5 mAh g-1 after 300 cycles. This work establishes a correlation between heterostructured porous colloidal layers and Zn anode interface stability, providing a paradigm for designing high-performance metal anodes via the synergy of ionic confinement and interfacial charge transfer.