In-Situ Growth of FeBTC on Nickel Foam as a Flexible Electrode for High-Performance Asymmetric Supercapacitors

Transition metal-based metal–organic frameworks (MOFs) exhibit promising potential in applications of supercapacitors due to their high porosity, large surface area, and abundant redox active sites. However, to date, most of the reported electrodes based on MOFs are fabricated through mixing of MOFs with binders such as PVDF and Nafion and then depositing them onto conductive substrates. The use of binders significantly deteriorates the electrical conductivity of the whole electrode. Herein, we report a binder-free MOF-based electrode fabricated through in situ growing FeBTC onto Ni foam (NF) by a hydrothermal method. The as-fabricated FeBTC/NF electrode exhibited a high specific capacitance of 2809 mF cm^–2 at 2 mA cm^–2, and exceptional flexibility at bending angles of 0 to 150°. Using FeBTC/NF as a positive electrode and activated carbon (AC) as a negative electrode, an asymmetric supercapacitor (FeBTC/NF//AC/NF) was assembled, which possessed a specific capacitance of 345.14 mF cm^–2 at 4 mA cm^–2 with a retention rate of 78.80% after 5000 cycles and delivered a maximum energy density of 93.96 μWh cm^–2 (82.20 Wh kg^–1) and a maximum power density of 17500 μW cm^–2 (15311 W kg^–1).