Preparation and electrochemical properties of carbon cloth supported (Ni,Co)Se2/CNT composite materials

Abstract

The design and construction of novel structures composed of multiple highly active components is key to solving the problem of supercapacitor application limitations. Inspired by nanostructures with hierarchical frameworks with interconnection networks, we utilize the functional backbone structure of two-dimensional cobalt-based MOFs to construct a multi-component and multi-morphic synergistic energy storage system. Specifically, Co-MOFs were grown in situ on carbon cloth (CC) as a template by a hydrothermal method, introduced with Ni while added with different carbon materials (CNTs, GO, and CQDs), and then prepared by solvent-thermal selenization of (Ni,Co)Se₂/CNT-1. The results show that the interconnected network structure formed by the addition of CNTs not only enhances the conductivity but also improves the susceptibility of selenides to agglomeration. In addition, the active material was directly grown on the flexible carbon cloth, which led to the formation of a fast ion/electron transfer channel between (Ni,Co)Se₂/CNT-1 and a fluid collector. As a result, the specific capacitance of (Ni,Co)Se₂/CNT-1 was as high as 721.7 C g⁻¹ at a current density of 1 A g⁻¹. The retention of specific capacitance was 81.6% when the current density was increased from 1 A g⁻¹ to 10 A g⁻¹. In addition, in order to evaluate the practical function, an asymmetric supercapacitor was assembled by using (Ni,Co)Se₂/CNT-1 as the positive electrode and activated carbon (AC) as the negative electrode. Notably, the device has an operating potential of 1.6 V and features high energy density (an energy density of 49.3 W h kg⁻¹ at a power density of 800 W kg⁻¹) and excellent cycling stability (a specific capacitance retention of 77.7% after 1500 cycles).