Soluble salt assisted synthesis of hierarchical porous carbon-encapsulated Fe3C based on MOFs gel for all-solid-state hybrid supercapacitor

Hierarchical porous materials receive extensive attention due to their excellent electrode kinetic performance. Herein, a facile strategy is presented to fabricate hierarchical porous supercapacitor materials using NaCl-assisted MOFs gel as a structure-directing template. By controlling the additive amount of NaCl, hierarchical porous carbon-encapsulated Fe 3 C with tailored pore size distribution has been obtained with a high specific capacity of 184.1 mAh g −1 (602.3F g −1 ) at a current density of 1 A g −1 . The analysis of kinetics and impedance indicates that the tailored porosity can provide broad ion diffusion pathway and low charge-transfer resistance. Meanwhile, seawater was used instead of NaCl for preparing hierarchical porous carbon with good capacitive performance. When evaluated their practical applications, the assembled all-solid-state hybrid supercapacitor delivers a high energy density of 30.6 W h kg −1 at a power density of 600 W kg −1 , and even maintains an energy density of 15.5 W h kg −1 at a power density of 12000 W kg −1 with 86.5% capacity retention after 10,000 cycles. This work is anticipated to open up a new route of using MOFs gel and water-soluble salts for designing hierarchical porous electrode s materials, which pave the way for advanced utilization of MOFs gel and seawater.