Alcohol hydroxides regulate the growth of Ni-Co layered double hydroxides on carbon fiber cloth as supercapacitor electrode materials

Abstract

There is a need to design and fabricate Ni-Co layered double hydroxides (Ni-Co LDHs) with high specific capacity, rate capability, and energy density for use as supercapacitor electrode materials. In this study, Ni-Co LDHs are directly grown on the flexible carbon fiber cloth (CFC) substrate by low-carbon alcohol/water solvothermal method. It is found that the morphology of Ni-Co LDHs changes from a wire-like structure to a lamellar structure because of the increased number of alcoholic hydroxyl groups, and the wire-like structure is more favorable for charge transfer and ion diffusion. The number of alcoholic hydroxyl groups has a greater impact on the morphological and electrochemical properties of Ni-Co LDHs compared with the n-propanol content. The Ni-Co LDH@CFC with well cycling stability can be obtained at a n-propanol/water volume ratio of 6:4 and a Ni/Co molar ratio of 1:1. The specific capacity reaches 1102 C g−1 at 2 A g−1 and 70% of the initial capacitance can be retained at 30 A g−1. A button-type asymmetric supercapacitor (ASC) Ni-Co LDH@CFC//AC with an energy density of 39 Wh kg−1 and a power density of 1450 W kg−1 has been successfully fabricated. This work may provide insights into the preparation of high-performance electrode materials with tunable architectures by regulating the number of alcoholic hydroxyl groups.