Preparation and characterization of flowerlike Al-doped Ni(OH)2 for supercapacitor applications

Flowerlike Al-doped Ni(OH)2 with different mole ratios of Ni2+/Al3+ were synthesized using hydrothermal method in ethanol solution. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Brunauer-Emmetto-Teller (BET) plot of nitrogen adsorption/desorption isotherms were used to characterize the structure changes of the synthesized samples, and electrochemical measurements were used to study the effect of Al on the electrochemical performance of flowerlike Al-doped Ni(OH)2. The results showed that flowerlike Al-doped Ni(OH)2 has a mixed phase of pure Ni(OH)2 and NiAl layered double hydroxide. Aluminum improves the 3-dimensional flowerlike structure, significantly increases the specific surface area and enhances the electrochemical performance of reversibility, rate capability and cyclic stability of Al-doped Ni(OH)2, but also seriously reduces the specific capacitance. This work suggested that aluminum content is an important factor that needs to be considered when flowerlike Al-doped Ni(OH)2 is used as electrode material for supercapacitor applications.