Highly scalable and pH stable 2D Ni-MOF-based composites for high performance supercapacitor

Abstract

Supercapacitors are projected as one of the most promising candidates for next-generation energy storage devices. Herein, we strategically developed a microporous two-dimensional Ni-metal organic framework (MOF: IITKGP-20A, IITKGP stands for the Indian Institute of Technology Kharagpur) which is highly scalable and thermodynamically stable over a wide pH range (2–10), intended for energy storage applications. Graphene oxide (GO) with different wt% (3, 5, and 7) was introduced with the MOF precursors to form in-situ MOF@GO composites (IITKGP-20A-GO3, IITKGP-20A-GO5, and IITKGP-20A-GO7 respectively), out of which IITKGP-20A-GO3 exhibits significantly high specific capacitance value (∼840 F g−1 at 2 A g−1), which is one of the highest among the bare MOFs and their composites/derived materials. To verify its practical potentiality as positive electrode material, an asymmetric supercapacitor (ASC) device was fabricated displaying the specific capacitance of 111.4 F g−1 at a current density of 2 A g−1 while maintaining a high specific capacity of 65 F g−1 even at a higher current density of 10 A g−1. Moreover, the device produced 30.7 W h kg−1 (0.031 W h cm−3) energy density with a very high power density of 388.5 W kg−1 (0.394 W cm−3) with excellent retention of 84% cycle life up to 7000 cycles.