Zn Powder Anodes With Stabilized Interfacial Chemistry via Facet‐Selective ZnTCPP Adsorption for Aqueous Zn‐Ion Batteries

Why It Matters

The breakthrough enables scalable, high‑performance zinc powder anodes, addressing safety and longevity challenges that have limited aqueous Zn‑ion batteries from commercial grid‑storage deployment.

Key Takeaways

• ZnTCPP selectively adsorbs on Zn(101) and Zn(100) facets
• Porphyrin ligands act as Zn2+ affinity centers, homogenizing ion flux
• Modified anode achieves 99.7% average Coulombic efficiency over 500 h
• Supports critical current densities up to 500 mA g⁻¹ without dendrites
• Full cells with ZnTCPP anodes show superior rate capability

Pulse Analysis

Aqueous zinc‑ion batteries have attracted attention as low‑cost, safe alternatives to lithium systems, yet scaling the anode from foil to powder introduces a new set of hurdles. The high surface area of Zn powder accelerates side reactions with the aqueous electrolyte, leading to uncontrolled dendrite formation, hydrogen evolution, and rapid capacity fade. Conventional coatings often fail to address both the crystallographic orientation and the chemistry of the interface, limiting cycle life and rate performance. Researchers therefore turned to metal‑organic frameworks, whose tunable porosity and functional groups can simultaneously modulate surface energetics and ion transport.

In the recent study, a porphyrin‑based MOF, zinc‑tetra(4‑carboxyphenyl)porphyrin (ZnTCPP), was grown in situ on Zn powder particles. The framework exhibits facet‑selective adsorption, anchoring preferentially to the high‑energy Zn(101) and Zn(100) planes, which suppresses their participation in metal deposition. Meanwhile, the porphyrin ligands provide strong Zn²⁺ affinity, creating a uniform ion flux that redirects nucleation toward the low‑energy Zn(002) facet, yielding compact, dendrite‑free growth. The MOF also catalyzes desolvation of hydrated Zn²⁺, reducing water‑related side reactions at the electrode surface.

Electrochemical testing shows the ZnTCPP‑coated powder delivers an average Coulombic efficiency of 99.7 % over 500 hours of plating/stripping and tolerates critical current densities up to 500 mA g⁻¹, far surpassing uncoated counterparts. Full‑cell configurations exhibit markedly improved cycling stability and rate capability, positioning the technology as a viable route for large‑scale, cost‑effective energy storage. By marrying surface crystallography control with interfacial chemistry engineering, the approach could accelerate commercialization of aqueous Zn‑ion batteries for grid‑level applications, where safety, material abundance, and long‑term durability are paramount.