In-situ constructing robust hydrophobic artificial interface layer to achieve a highly reversible dendrite-free Zn Anode for aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) have developed into a promising novel energy storage system by reason of their low cost, high safety and abundant natural reserves; however, uncontrolled dendrite growth and serious side reactions on the surface of Zn metal anode pose significant obstacles to their practical implementation. Herein, a high-bonding-strength hydrophobic artificial interface layer of zeolite imidazole framework-8 (ZIF-8) is in-situ constructed on the surface of Zn metal anode by the coordination reaction amid pre-oxidized commercial Zn foil and 2-methylimidazole (IZIF-8@Zn). The Zn metal electrode with in-situ grown protective layer processes low activation energy of 46.29 kJ mol−1 and high ionic conductivity of 4.28 mS cm−1, accelerating the interface transfer of zinc ions; moreover, the in-situ grown ZIF-8 layer with the excellent adhesion to zinc, strong hydrophobicity and high porosity may separate Zn metal from aqueous electrolyte, act as a desolvation layer for Zn ions and homogenize the distribution of Zn2+ on anode surface, inhibiting side reactions, restricting 2D diffusion, promoting Zn deposition kinetics and thus squelching dendrite growth. Consequently, the IZIF-8@Zn||IZIF-8@Zn symmetric cell indicates a high-stable lifespan over 2000 h at 0.5 mA cm−2 and 0.5 mAh cm−2 and delivers the average Coulombic efficiency (CE) of 99.59 % at 1 mA cm−2 and 1 mAh cm−2. Moreover, the IZIF-8@Zn//VO2 full-cell possesses a high initial capacity of 147 mAh g−1 at 5 A g−1 with the excellent capacity retention of 71.80 % after 1000 cycles. This investigation proposes a useful strategy for in-situ growing the protective layer with unique characteristics of structure and micromorphology on the surface of metal anodes to effectively prohibit side reactions and dendrite growth.