Surface coatings of two-dimensional metal-organic framework nanosheets enable stable zinc anodes

Aqueous zinc-ion batteries (ZIBs) have been considered as safe and scalable energy storage solutions, but the dendrite and corrosion issues of Zn anodes have hindered their further application. Herein, we demonstrate that two-dimensional metal-organic framework (MOF) nanosheets can act as protective coatings to prevent dendrite formation and hydrogen evolution of Zn anodes. The morphology of MOFs was tuned from octahedral nanoparticles (UiO-67-3D) to nanosheets (UiO-67-2D), leading to significantly enhanced protective performance. UiO-67-2D nanosheets-coated Zn anodes displayed smaller polarization, longer cycling lifetime and lower H2 evolution than those of UiO-67-3D nanoparticles in symmetrical cells, which has been attributed to the higher concentration of surface Zr−OH/H2O to induce uniform Zn deposition and one-dimensional (1D) channels perpendicular to the Zn surface to regulate Zn2+ diffusion. The assembled UiO-67-2D@Zn∥Mn2O3/C full cell shows a high capacity of 240 mAh g−1 at 1 A g−1 and excellent cycling stability.