Separator of polyacrylonitrile modified with Prussian blue analogs for high-efficiency aqueous zinc-ion batteries

Abstract

Because of their safety and cost-effectiveness, aqueous zinc-ion batteries (AZIBs) have emerged as promising candidates for large-scale energy storage applications. However, Zn dendrite growth on metallic zinc anodes severely affects their cycling stability and coulombic efficiency. Herein, a polyacrylonitrile separator modified with FeNi-based Prussian blue analog (FeNi-PBA@PAN) was rationally designed and prepared, which could serve as an ion sieve for AZIBs. Its inherent robust cationic sites hamper the mobility of SO₄²⁻ anions, whereas the mobility of Zn²⁺ is improved with a transference number of 0.81, resulting in a homogeneous Zn²⁺ flux and interfacial electric field on the surface of the zinc anode, thus suppressing the growth of Zn dendrites. The assembled Zn‖Zn symmetric battery using FeNi-PBA@PAN as a separator exhibits highly reversible plating/stripping behavior with a prolonged cycle life of over 2700 hours at a current density of 1 mA cm⁻². Moreover, the Zn|FeNi-PBA@PAN|MnO₂/CNT full battery shows increased specific capacity and sustained durability, showcasing an impressive capacity retention rate of 81% even after undergoing 2000 cycles at a current density of 2 A g⁻¹. Our study thus paves a new avenue for the design and development of new separators for AZIBs without zinc dendrites.