Guiding uniform zinc ion flux with 18-Crown-6 additives for highly reversible Zn metal anodes

Zn metal batteries prove favourable applications in wide-scale energy storages but suffers from irreversible dendrite growth, severe hydrogen evolution and corrosion reaction. Here, a ring additive, 18-Crown-6 (18C6), is adopted to achieve long-term and highly reversible Zn plating/stripping. The non-polar structure and large inner cavity diameter of 18C6 can homogenize Zn2+ flux and enhance Zn2+ deposition kinetics. Moreover, 18C6 self-assembles on the surface of Zn anode to form a protective film, which accelerates the Zn2+ desolvation during deposition process and realizes the physical barrier between Zn anode and water molecules. As expected, the cycle life of the Zn//Zn symmetrical cells reaches over 4200 h at 0.5 mA cm−2 and 0.5 mAh cm−2 in 18C6-containing electrolytes. In addition, the Zn//p-phenylenediamine-intercalated vanadium phosphate full cell presents distinguished cycling stability for 2500 cycles at 5 A/g. Given the low-cost superiority of 18C6, the proposed electrolyte optimization strategy exhibits appreciable potential in facilitating the commercialization progress of aqueous Zn metal batteries.