Interlayer Hydrogen-Bonded Metal Porphyrin Frameworks/MXene Hybrid Film with High Capacitance for Flexible All-Solid-State Supercapacitors.

2D metal-porphyrin frameworks (MPFs) are attractive for advanced energy storage devices. However, the inferior conductivity and low structural stability of MPFs seriously limit their application as flexible free-standing electrodes with high performance. Here, for the first time, an interlayer hydrogen-bonded MXene/MPFs film is proposed to overcome these disadvantages by intercalation of highly conductive MXene nanosheets into MPFs nanosheets via a vacuum-assisted filtration technology. The alternant insertion of MXene and MPFs affords 3D interconnected "MPFs-to-MXene-to-MPFs" conductive networks to accelerate the ionic/electronic transport rates. Meanwhile, the interlayer hydrogen bonds (F···HO and O···HO) contribute a high chemical stability due to a favorable tolerance to volume change caused by phase separation and structural collapse during the charge/discharge process. The synergistic effect makes MXene/MPFs film deliver a capacitance of 326.1 F g-1 at 0.1 A g-1 , 1.64 F cm-2 at 1 mA cm-2 , 694.2 F cm-3 at 1 mA cm-3 and a durability of about 30 000 cycles. The flexible symmetric supercapacitor shows an areal capacitance of 408 mF cm-2 , areal energy density of 20.4 µW h cm-2 , and capacitance retention of 95.9% after 7000 cycles. This work paves an avenue for the further exploration of 2D MOFs in flexible energy storage devices.