Interface-Synergistic Sulfonated Phthalocyanine Enabling Simultaneous Dendrite Suppression and Shuttle Mitigation in High-Rate Static Zinc–Iodine Batteries

Static zinc–iodine batteries (SZIBs) offer high capacity, safety, and low cost for large-scale energy storage, but suffer from zinc dendrite growth and polyiodide shuttle effects. Here, a sulfonated cobalt phthalocyanine (S-CoPc) is introduced as a dual-functional additive to simultaneously stabilize the zinc anode and iodine cathode. Hydrophilic sulfonic groups enable uniform dispersion in aqueous electrolyte, while zincophilic sites and Co–N4 centers regulate Zn2+ deposition and iodine redox reactions. At the anode, S-CoPc adsorption homogenizes Zn2+ flux (finite-element verified) and lowers desolvation energy barriers, achieving dendrite-suppressed plating and long-term stability over 2800 h in Zn||Zn cells. At the cathode, strong I3– chemisorption and accelerated I–/I2 conversion kinetics mitigate the shuttle effect and enhance redox reversibility. The optimized SZIB delivers 219.8 mAh g–1 at 1 A g–1, retains 105.6 mAh g–1 at 30 A g–1, and maintains 96.7% capacity after 10,000 cycles at 10 A g–1. A high-loading pouch cell (1.7 mAh cm–2) achieves 86.5% retention after 550 cycles, demonstrating the potential of S-CoPc-enabled electrolyte engineering for durable, high-rate aqueous batteries.