Construction of Cation-Sieving Function Layers Enabling Dendrite-Free Zinc Metal Anodes for Durable Aqueous Systems

Rechargeable aqueous zinc-ion batteries are considered as promising candidates for safe and green energy storage. Yet, Zn anodes still suffer from serious challenges. Herein, an effective cation-sieve of polyethersulfone-modified sulfonated polyether ether ketone is developed as protective coating layer of the Zn anodes. Cation-only transmission and dense property of the layer can protect the Zn from active water and anions, inhibiting corrosion, hydrogen evolution reaction (HER), and passivation. Zincophilic property of the layer can homogenize Zn²⁺ flow, and promote uniform plating of Zn. Therefore, protected symmetric Zn||Zn cell can maintain as long as 5600 h with a low polarization at 1.0 mA cm^-2 and 0.5 mAh cm^-2, and still long as 800 h at 5.0 mA cm^-2 and 5.0 mAh cm^-2. It is found that not only the dendrites but also the popular existed passivation product of Zn₄SO₄(OH)₆·5H₂O can be inhibited effectively. In asymmetric Zn||Ti cells, average Coulombic efficiency can reach 98.2%, suggesting corrosion and HER are restrained effectively. Matched with MnO₂ cathode, full cells using coated Zn exhibit much better cycling performance than that using bare Zn. Moreover, Zn₄O₃(SO₄)·7H₂O (ZSH)-assisted reversible conversion mechanism between the ZSH and Zn_xH_yMnO₂ is revealed through operando Raman.