Effect of soft templating agent on NiCoAl-LDHs grown in situ on foamed nickel for high-performance asymmetric supercapacitors

Abstract

In this paper, NiCoAl-LDHs were synthesized by hydrothermal method with polyvinyl alcohol, polyvinylpyrrolidone, cetyltrimethyl ammonium bromide, and sodium dodecyl sulfate as templating agents, and these materials directly grew on foamed nickel. The electrochemical performance of these materials was investigated by galvanostatic charge/discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. The morphology and physicochemical properties of the materials were characterized by X-ray diffraction and scanning electron microscopy. The results showed that the NiCoAl electrode with the usage of 1.00 g polyvinyl alcohol, 1.00 g polyvinylpyrrolidone, 1.00 g cetyltrimethyl ammonium bromide, and 1.00 g sodium dodecyl sulfate and non-template agents showed high capacitance of 1413.2, 1553, 1648.4, and 1420 and 1068 F g−1 at 1 A g−1. It had excellent rate performance and cycle stability. After the 2000-cycle charge/discharge test at a current density of 10 A g−1, the capacity of the materials’ retention rates was 82.68%, 80%, 88.4%, 90%, and 83.45%, respectively. An asymmetric supercapacitor (ASC) based on C-NCA electrode and activated carbon electrode achieved an excellent electrochemical property with the energy density of 75.55 Wh kg−1 at the power density of 800 W kg−1 and good cycling stability (retaining 89.87% after 2000 cycles). In summary, the prepared sample can be an ideal electrode material for a supercapacitor.