In Situ Constructed Zn3N2‐Enriched Hybrid Solid Electrolyte Interphase Enables Highly Efficient Zinc Deposition Kinetics for Ultra‐Stable Zinc‐Iodine Batteries

Why It Matters

The breakthrough tackles dendrite growth and sluggish charge transfer that have hampered zinc‑based batteries, enabling long‑life, high‑power storage for grid and portable applications. Such stability could accelerate commercialization of safe, low‑cost aqueous batteries.

Key Takeaways

• FCP additive forms Zn3N2‑rich hybrid SEI in situ.
• Hybrid SEI accelerates Zn2+ migration and desolvation.
• Uniform Zn plating achieved, suppressing dendrite growth.
• Symmetric cells cycle >6000 times at 20‑50 mA cm⁻².
• Full Zn‑I2 battery retains 80.9% capacity after 65,000 cycles.

Pulse Analysis

Aqueous zinc‑iodine batteries have attracted attention for their low cost and intrinsic safety, yet practical deployment has been stymied by rapid zinc dendrite formation, side‑reaction‑induced passivation, and the polyiodide shuttle that slows charge transfer. Traditional solid electrolyte interphases (SEIs) often lack sufficient ionic conductivity, leading to uneven plating and premature failure. Addressing these bottlenecks requires an interphase that not only protects the metal surface but also actively facilitates ion transport and mitigates shuttle effects.

Enter copper hexadecafluorophthalocyanine (FCP), a macrocyclic additive that self‑assembles during cycling to generate a Zn3N2‑rich hybrid SEI. The inorganic Zn3N2 component offers a lattice conducive to rapid Zn2+ migration, while the organic π‑conjugated backbone creates a delocalized electric field that lowers the desolvation barrier for hydrated Zn2+. This dual‑function architecture also promotes in‑plane electron transport, further accelerating interfacial kinetics. Moreover, FCP molecules preferentially adsorb onto the zinc surface, guiding uniform nucleation and suppressing dendritic protrusions.

The performance gains are striking: symmetric Zn cells sustain over 6,000 cycles at ultra‑high current densities of 20–50 mA cm⁻², and a full Zn‑I2 cell retains more than 80% of its capacity after 65,000 cycles at a 50 C rate. Such durability and rate capability position this chemistry as a strong candidate for grid‑scale storage, electric vehicles, and remote power systems where safety and longevity are paramount. Continued optimization of hybrid SEI chemistries could further reduce overpotentials and extend cycle life, accelerating the transition from laboratory prototypes to commercial aqueous battery solutions.