Robust Hybrid Solid Electrolyte Interface Induced by Zn‐Poor Electric Double Layer for A Highly Reversible Zinc Anode

Aqueous Zn‐ion batteries (AZIBs) show great potential in new energy storage devices due to low cost, inherent safety, and environmental friendliness. However, the severe dendrites and side reactions on the anode greatly constrain their practical application. Herein, a novel colloidal electrolyte composed of ZnSO 4 and sodium carboxymethyl cellulose (CMC‐Na) has been developed for inhibiting dendrite growth on Zn anode. Molecular dynamics (MD) simulation confirms that CMC‐Na alters the electric double layer (EDL) structure of Zn anode surface to reduce the content of water and SO 4 2− and inhibit side reactions. More importantly, an organic/inorganic hybrid solid electrolyte interface (SEI) layer is in situ constructed during the cycling, which enables ultrastable Zn plating/stripping (> 2000 h) under high current density (5 mA cm −2 , 5 mAh cm −2 ) and high coulombic efficiency (99.8%) for more than 1000 cycles. Meanwhile, zinc‐ion hybrid capacitors (ZIHCs) with the colloidal electrolyte exhibit a favorable capacitance retention of 97% after 15000 cycles at the current density of 2 A g −1 . Even at a high current density of 5 A g −1 , it still has a capacitance retention of 96% after 30000 cycles. This study presents a novel electrolyte strategy for the formation of ultrastable electrode‐electrolyte interfaces in AZIBs.