15-Crown-5 ether as efficient electrolyte additive for performance enhancement of aqueous Zn-ion batteries

•15-crown-5 ether is added into ZnSO4 electrolyte to mitigate side reactions over the Zn anode.•Only 2 wt% 15-CE-5 in the electrolyte can significantly prolong the lifespan of Zn anode.•Other types of CE molecules are also used as electrolyte additives for a comparison study.•Theoretical analysis reveals that the 15-CE-5 molecules can replace water molecules in the Zn2+ hydration sheath.