Realizing Lean‐Electrolyte Zinc‐Ion Batteries via An Ultrathin and Cost‐Effective Separator
Yurou Wu, Meilan Xie, Kai Fu, Zhendong Li, Huixin Shi, Jiarui Zhang, Lihan Wang, Yun-Liang Jiang, Cai‐ling Liu, Dui Ma, Hongbo Huang, Fanyan Zeng, Yaqi Liao, Han Liu, Yang Ren, Xiao Liang
Abstract
Abstract Ultrathin separators accompanied with lean electrolyte conditions are highly desirable for developing high‐energy‐density aqueous Zn‐ion batteries (AZIBs). Herein, a 10 µm separator (PGZ) is designed via a facile and cost‐effective strategy. Experiments and theoretical simulations demonstrated that high polar β ‐PVDF in PGZ separator permits rapid Zn 2+ transfer while blocking OTf – , I 3 – , I 5 – , and H 2 O, effectively homogenizing the Zn 2+ flux, preventing polyiodide shuttle, and suppressing parasitic reactions. Moreover, the ultrathin separator enables a reduced electrolyte usage to 2 µL mg −1 , significantly increasing the energy density. Consequently, Zn/Zn symmetric cells with the PGZ separator stably cycle for 3500 h at 0.5 mA cm −2 @0.5 mAh cm −2 . The Zn/I 2 full cells exhibit ultralong cyclic stability over 23 000 cycles at 5C (≈240 days). Even at harsh conditions of high I 2 loading (10.4 mg cm −2 ), low E/A ratio (2 µL mg −1 , electrolyte volume per active material), and low N/P ratio (3.9), superior cycling performance (2750 cycles with 93.1% capacity retention) and high gravimetric energy density (129.7 Wh kg −1 ) are obtained. This work presents a simple and cost‐effective strategy for designing ultrathin separators for achieving stable lean‐electrolyte and high‐energy‐density AZIBs.