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 Fe3C 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 electrodes materials, which pave the way for advanced utilization of MOFs gel and seawater.

Automated summary

A facile strategy was presented to fabricate hierarchical porous supercapacitor materials using NaCl-assisted MOFs gel as a structure-directing template, which can provide broad ion diffusion pathway and low charge-transfer resistance. The use of seawater instead of NaCl for preparing hierarchical porous carbon also showed good capacitive performance, demonstrating potential for advanced utilization of MOFs gel and seawater in designing electrodes materials.