Construction of Battery-Like Hierarchical MOF@MXene Heterostructures for Hybrid Supercapacitors

Presently, two-dimensional (2D) hybrid metal–organic framework (MOF) heterostructures have drawn much attention in energy-storage areas. Rapid transport and full diffusion of ions could favor the full utilization of active sites, giving 2D MOF heterostructures a robust electrochemical performance. Herein, to optimize ion transport paths and promote ion penetration ability, a block copolymer was used to produce mesopores inside 2D MOF nanosheets, constructing a hierarchically porous MOFs@MXene hybrid. The energy-storage mechanism analysis shows that diffusion-controlled behaviors play a dominant role over surface capacitive behaviors in storing charges of the hierarchical hybrids. The resulting Meso-Cu-Zn-MOFs@Ti3C2Tx delivers a capacity of 61.8 mA h g–1 (404 F g–1) at 0.2 A g–1 and a good rate capacity (53 and 44.4 mA h g–1 at 1 and 5 A g–1, respectively). Furthermore, an assembled Meso-Cu-Zn-MOF@Ti3C2Tx//AC hybrid device exhibits an energy density of 35.6 W h kg–1 at a power density of 425.8 W kg–1 (0.5 A g–1) and a power density of 4.25 kW kg–1 at an energy density of 27.1 W h kg–1 (5 A g–1).