Demonstrating U-shaped zinc deposition with 2D metal-organic framework nanoarrays for dendrite-free zinc batteries

Aqueous zinc (Zn) battery has shown its great promise as intrinsically safe battery technology. However, Zn batteries are still far from practical use, mainly due to Zn dendrite growth and side reactions. We propose a U-shaped deposition configuration to address the dendrite issue of Zn anode, which is achieved within a nanoarray of 2D metal-organic framework (MOF) flakes grown on the Zn anode. Rich zincophilic sites of the flakes enable uniform pre-seeding of Zn ions, followed by lateral deposition of Zn metal onto the MOF flakes and bottom-up plating from the anode surface, finally achieving a U-shaped deposition. The U-shaped deposition configuration is well demonstrated by simulation results in which the ion concentration and current distribution are regulated by the MOF arrays. This procedure combining pre-seeding and bottom-up deposition naturally eliminates the “tip effect” and inhibits Zn dendrite. Together with the ideal suppression of the hydrogen evolution reaction, the Zn metal anode features long cycling stability up to 1880 h at a current density of 5 mA cm−2 and extends the long lifespan to full cells. This study demonstrates a renewed understanding of controlling Zn deposition in practical batteries and paves a new avenue toward dendrite-free metal anodes.