Dual-functional cellulose separator regulating Zn deposition for long lifespan zinc-based energy storage

Aqueous zinc-ion batteries (ZIBs) hold significant promise for next-generation energy storage due to their low cost and inherent safety, but their lifespan is limited by zinc dendrites and hydrogen evolution during the cycling. Herein, long lifespan ZIBs are achieved using a dual-functional separator with ultrathin (18 μm) and high mechanical strength (91 MPa). The abundant polar hydroxyl groups in the separator's structure repel free SO₄^2- anions, accelerate the Zn²⁺ ion transport, and modify the solvation structure of Zn(H₂O)₆²⁺, ensuring uniform Zn²⁺ ion flux and inhibiting zinc dendrite formation. Consequently, the Zn//Zn symmetrical cells with dual-functional separators exhibit superior electrochemical performance, with a cycle life exceeding 1100 h at 1 mA cm^-2 and 440 h at 10 mA cm^-2, 5-9 times longer than cells using glass-fiber separators. The zinc-ion hybrid supercapacitor with the functional separator achieves a high capacity retention ratio (93.1 %) after 1000 cycles at 1.0 A g^-1. This work offers new insights into the development of multifunctional separator for high-performance zinc-based energy storage.