Carbon/Layered Double Hydroxide (LDH) Composites for Supercapacitor Application

In this paper, layered double hydroxide (LDH)/activated carbon composite electrodes for use in an electrochemical capacitor have been prepared by a simple chemical precipitation of hydroxy-carbonates from the homogeneous solution of metal salts and urea after the thermally induced hydrolysis of urea. Subsequently, the LDH has been converted into other forms of oxides by thermal treatment. Physical properties, morphology, and specific surface area of prepared materials were characterized by X-ray diffraction and energy-dispersive spectroscopy, scanning and transmission electron microscopy (SEM and TEM), and nitrogen sorption measurements. SEM images confirmed uniform and hexagonal platelets of LDH well-dispersed on the carbon material external surface. The electrochemical performance of the composite electrodes was studied by cyclic voltammetry, galvanostatic charge/discharge measurements, and impedance spectroscopy. Introducing a small amount of LDH to activated carbon improved electrochemical properties of the electrode, which is a result of a combination of the redox reactive property from LDH and good electronic conductivity of the carbon host. High Brunauer-Emmett-Teller (BET) surface area of the LDH/carbon composite can be accessible to the electrolyte in a micro-/mesoporous network. Moreover, a symmetric capacitor based on carbon/LDH composite electrodes retains the value of specific capacitance after long cycling and at high current density.