Exploring the electrochemical synergy of metal sulfides and metal-organic framework composite as hybrid supercapacitor electrodes

Abstract

Metal-organic frameworks (MOFs) are promising electrode materials however, they continue to seek improvements in both energy density and electrical conductivity. Within a wide array of available metal nodes and linkers, the task of refining and attaining a profound comprehension of charge storage mechanisms is still to accomplish. Herein nickel sulfide and nickel MOF were synthesized via hydrothermal method, their properties were investigated, and a binary composite was developed due to the high resistance of pristine MOFs. This composite demonstrated exceptional specific capacity of 787.8 C/g at cost of 2.0 A/g. To leverage real-world applications, a supercapattery was fabricated using the NiS/Ni-MOF as the positive electrode material and activated carbon as the negative electrode material. The device possesses maximum specific energy of 64.67 Wh/kg and maximum specific power of 3200 W/kg together with capacity retention of 91 % after 5k charge-discharge cycles. To validate results, semi-empirical approach using Dunn’s model and power law is subjected to investigate the capacitive and diffusive contributions and b-values. This study shows that the binary composites of metallic sulfides with MOFs can possess potentials for their applications in real devices.