Molecular Electrocatalyst with Local Dipole Enhances Iodine Redox Kinetics for High-Areal-Capacity Zn–I 2 Batteries

Aqueous zinc-iodine (Zn–I2) batteries are promising for large-scale energy storage but are hindered by capacity fade caused by the polyiodide shuttle. Herein, an amino-functionalized nickel phthalocyanine molecular electrocatalyst (TAPc-Ni) is designed to simultaneously optimize iodine adsorption/desorption and electron transport via a high-activity Ni–N4 center and a tuned π-conjugated backbone. The −NH2 groups enrich electron density in the phthalocyanine macrocycle through p−π conjugation, generating a local dipole such that both −NH2 and the Ni–N4 center act as dual I3– anchoring sites. Meanwhile, the π-conjugated framework serves as an “electron sponge,” channeling electrons through −NH2 sites toward the Ni–N4 center to facilitate redox kinetics. DFT calculations and in situ characterizations confirm that TAPc-Ni reduces the energy barrier of iodine redox and effectively suppresses polyiodide shuttling. Consequently, the Zn–I2 battery incorporating a TAPc-Ni@ACC electrocatalytic interlayer delivers an areal capacity of 6.7 mAh cm–2 after 1000 cycles at 5 C. This work provides a versatile strategy for tailoring metallic phthalocyanine-based molecular electrocatalysts toward high-areal-capacity Zn–I2 batteries.