Regulating Exposed Facets of Metal-Organic Frameworks for High-rate Alkaline Aqueous Zinc Batteries

Abstract

Metal-organic frameworks (MOFs) have drawn growing attention as promising electrode candidates for rechargeable batteries. However, most studies focus on the direct use of MOF electrodes without any modification. Post-synthetic modification, a judicious tool to modify targeted properties of MOFs, has been long-neglected in the field of batteries. Herein, crystal-facet engineering is proposed to design MOF-based electrodes with high capacity and fast electrochemical kinetics. We found that a thermally-modified strategy can regulate the dominant exposed facet of Ni-based MOF (PFC-8). With the optimally exposed facets, the battery exhibited admirable rate capability (139.4 mAh g⁻¹ at 2.5 A g⁻¹ and 110.0 mAh g⁻¹ at 30 A g⁻¹) and long-term stability. Furthermore, density functional theory calculations demonstrate that stronger OH⁻ adsorption behaviors and optimized electronic structures induced by the regulated exposed facets boost the electrochemical performance.