Effect of B doped on capacitance properties of NiO/Ni(OH)2 electrode materials

Abstract:

Two electrode materials, homogeneous NiO/Ni(OH)₂ with micropits and NiO/Ni(OH)₂(B) with microspheres, were prepared on the surface of copper sheet by electroless plating and subsequent electrochemical anodic oxidation. The results of SEM, XRD and XPS showed that the two electrode materials were composed of Ni, NiO and Ni(OH)₂, and the doped of B in NiO/Ni(OH)₂(B) was up to 14.6wt%. The cyclic voltammetry measurements and galvanostatic charge-discharge tests show that both electrode materials possess high electrochemical activity and reversibility. At the charge/discharge current density of 1 A/g, the specific capacitance of 1380 and 1930F/g of two kinds of NiO/Ni(OH)₂ and NiO/Ni(OH)₂(B) electrode materials after 10000 charge/discharge cycles are respectively obtained, showing high specific capacitance and good electrochemical stability. The electrochemical impedance spectroscopy shows that the electrochemical reaction resistance of NiO/Ni(OH)₂(B) electrode material is about 2 orders of magnitude lower than that of NiO/Ni(OH)₂. The Ragone curve reveals that the two electrode materials have higher power density and lower energy density. The doped of B in the NiO/Ni(OH)₂(B) electrode materials increases the surface oxide content and forms micron microsphere morphology, which results in the increase of electrode surface area and the improvements of the contact and wettability between the electrode and the electrolyte, and the decrease of the band gap energy on the surface of electrode. These are the main reasons for its excellent pseudo-capacitance performance.

Key words:Electrochemical capacitor; NiO/Ni(OH)₂ electrode materials; B-doped; specific capacitance; electrochemical anodic oxidation