Synergy between central zinc coordination and extended π-conjugation: Zinc phthalocyanine as an optimal artificial interphase for highly reversible aqueous zinc metal anodes

Abstract

Aqueous zinc-ion batteries are promising for low-cost, safe large-scale energy storage, yet their practical deployment is plagued by zinc dendrite growth and water-induced side reactions. Herein, four structurally defined conjugated macrocycles (Tpp, Pc, ZnTpp, ZnPc) are employed as Zn anode protective coatings to establish molecular structure−performance correlations. Experimental and theoretical results reveal that ZnPc integrates the dual advantages of central Zn coordination and extended π-conjugation to optimize interfacial stability. The zinc-coordinated center acts as zincophilic sites to reduce nucleation overpotential and suppress hydrogen evolution by lowering the LUMO level, while the large π-network boosts electrical conductivity, accelerates ion desolvation, increases Zn transference number, and imparts hydrophobicity to isolate water. Benefiting from these synergistic effects, the ZnPc-modified Zn anode achieves ultra-long symmetric cycling (2000 h), a high Coulombic efficiency of 99.53% over 2500 half-cell cycles, and superior full-cell stability with a capacity retention of 75.74% after 5000 cycles. This work proposes a reliable molecular engineering strategy for high-stability Zn anodes, offering insights into advanced aqueous battery design.