Electrostatic co-assembly derived mesoporous polyoxometalate-intercalated polyaniline hybrid nanospheres for stable zinc-ion batteries

Abstract Aqueous zinc-ion batteries (AZIBs) are promising large-scale energy storage devices, yet their practical application is severely restricted by cathode materials suffering from sluggish ion transport kinetics and poor cyclic stability. Organic polyaniline cathodes feature tunable redox sites and mechanical flexibility, but dense chain stacking and drastic volume expansion degrade their capacity and lifespan. Herein, we propose an electrostatic co-assembly and confined template polymerization strategy to fabricate mesoporous vanadium‑manganese polyoxometalate-intercalated polyaniline hybrid nanospheres (mPANI@POM). Negatively charged colloidal silica (SiO2) serves as sacrificial templates to guide uniform adsorption of protonated aniline, while anionic POM clusters are electrostatically intercalated into polyaniline chains to form an organic–inorganic hybrid after template etching. The interconnected mesoporous framework shortens Zn2+/H+ diffusion paths, and the synergistic dual redox centers of conjugated polyaniline and multi-electron vanadium–manganese polyoxometalate greatly accelerate charge transfer. The mPANI@POM cathode achieves 264 mAh g–1 at 0.5 A g–1, retains 147 mAh g–1 at 3.0 A g–1, and exhibits good cycling stability with 90.6% capacity retention after 1000 cycles at 5.0 A g–1. Combined in-situ characterizations verify that energy storage relies on synergistic reversible benzenoid–quinoid transformation and reversible V/Mn–O coordination evolution. This electrostatic co-assembly strategy offers a universal route to design high-performance organic–inorganic hybrid cathodes for durable AZIBs