Stabilizing Zinc Anodes by a Cotton Towel Separator for Aqueous Zinc-Ion Batteries

The poor electrochemical stabilities of aqueous zinc-ion batteries (AZIBs) are mainly related to the uncontrollable dendrite growth, hydrogen evolution, and side reactions. Here, a commercial cotton towel (CT) is directly developed as a separator of AZIBs to mitigate these problems. This CT separator effectively buffers the hydrogen evolution and side reactions to enhance the reversibility of a Zn anode. Additionally, the strong coordination between the hydroxyl group in the CT separator and Zn2+ significantly constrains two-dimensional surface diffusion of Zn atom and increases nucleation sites, further regulating uniform Zn deposition, which effectively cushions Zn dendrite formation. Accordingly, the symmetric cell equipped with the CT separator displays an ultralong lifespan of over 1200 h at 1 mA cm–2 for 0.5 mAh cm–2 and 700 h at 2 mA cm–2 for 4 mAh cm–2. Notably, the CT separator significantly boosts the cyclability of a MnO2 full cell at 1 A g–1 (96.9 mAh g–1 after 2400 cycles). A flexible soft-packaged cell consisting of CT enables an impressive electrochemical performance. Such a high-performance separator with attractive cost effectiveness provides a potential prospect for large-scale applications of AZIBs in electrochemical energy storage devices and wearable electronics.