Effects of ball milling on the physical and electrochemical characteristics of nickel hydroxide powder

Abstract

Nickel hydroxide powder was modified by the method of ball milling, and the physical properties of both the ball-milled and un-milled nickel hydroxide were characterized by scanning electron microscopy, specific surface area, particle size distribution and X-ray diffraction. It was found that the ball milling processing could obviously increase the surface area, decrease the particle and crystallite size, and reduce the crystallinity of b-Ni(OH) 2 , which was advantageous to the improvement of the electrochemical activity of nickel hydroxide powder. Electrochemical performances of pasted nickel electrodes using the ball-milled nickel hydroxide as an active material were investigated, and were compared with those of the electrodes prepared with the un-milled nickel hydroxide. Charge/ discharge tests showed that the ball-milled nickel hydroxide electrodes exhibited better performances in the charging efficiency, specific discharge capacity, active material utilization and discharge voltage. The improvement of the performances of b-Ni(OH) 2 through ball milling could be attributed to the better reaction reversibility, higher coulombic efficiency, higher oxygen evolution potential and lower electrochemical impedance, as indicated by the cyclic voltammetry and electrochemical impedance spectroscopy studies. Thus, ball milling was an effective method to modify the physical properties and enhance the electrochemical performances of nickel hydroxide powder for the active material of rechargeable alkaline nickel batteries.

Effective Utilization of Waste Red Mud for High Performance Supercapacitor Electrodes

“…CV scans were executed using a 0.1 m KCl aqueous solution containing 5 × 10 −3 m Fe(CN) 3−/4− redox couple within a scan range −0.30 to +0.70 V with a scan rate of 50 mV s −1 . [64] ΔE diff was measured to be ≈258 mV for RM-0 sample, indicating the redox reaction is somewhat quasi-reversible in nature. With increased milling time, the peak currents are found to enhance, with maximum peak currents of 59.1 and −58.0 A g −1 observed in RM-10.…”

“…The separation potential (the difference between the anodic and cathodic peak potentials) (ΔE diff ) is a qualitative measurement of reversibility of redox reactions, where a smaller value indicates a better reversibility. [64] ΔE diff was measured to be ≈258 mV for RM-0 sample, indicating the redox reaction is somewhat quasi-reversible in nature. The ΔE diff for RM-3 sample was found to be ≈313 mV implying a poor reversibility.…”

Use of spray technique to prepare Ni/Al-layered double hydroxides

“…The average peak potential, E rev , is taken as an estimate of the reversible potential and the difference between the anodic and cathodic peak position, E a,c , is taken as an estimate of the reversibility of the redox reaction. The smaller is E a,c , the more reversible is the electrochemical reaction [21]. The electrodes with sample A have smaller E a,c than those with sample B, and thus have better electrochemical reversibility.…”

Electrochemical performance of multi-element doped α-nickel hydroxide prepared by supersonic co-precipitation method

“…3 are tabulated in Table 2. The E OR is taken as an estimate of the reversibility of the redox reaction, the smaller is E OR , the more reversible is the electrochemical reaction [19]. The sample C has smaller E OR than the others, and thus has better electrochemical reversibility in charge-discharge process.…”