Fabrication and assembly of supercapacitors based on Ni-based MOFs and their derivative materials for enhancing their electrochemical performances

Abstract

Metal–organic frameworks (MOFs) are a class of porous materials that have been gradually applied in the field of supercapacitors, but they still present major challenges due to their inherent instability and poor conductivity. Herein, in order to solve these problems, Ni-based MOFs and their derivative materials with a particular spherical structure were prepared using a special calcination method. This unique structure not only improves the conductivity of the electrode, but also promotes the transport of electrons and ions during the electrochemical energy storage process. The as-prepared Ni-MOF@M-a4 has an amazing specific capacitance (637.78 F g⁻¹) and a relatively low impedance. The fabricated asymmetric supercapacitor (ASC) consisted of Ni-MOF@M-a4 and activated carbon (AC) as positive and negative electrodes, respectively. The specific capacitance of this ASC was 18.14 F g⁻¹. The maximum energy and power densities of the device reached 1.23 W h kg⁻¹ and 175.00 W kg⁻¹, showing good electrochemical performance. In this work, both an innovative strategy for the rational preparation of MOF arrays with good orientation and a special material preparation method are proposed, which have promising application potential in the field of asymmetric supercapacitors.