Mn-substituted nickel hydroxide prepared by ball milling and its electrochemical properties

In order to reduce the price of nickel hydroxide and extend the application of nickel based alkaline secondary batteries, Mn substituted nickel hydroxide (Ni1−xMnx(OH)2, x = 0–0.4) was prepared by using a simple ball milling method in this paper. The optimal ball milling conditions were obtained for the preparation of Ni0.8Mn0.2(OH)2. The results of X-ray diffraction, electrochemical impedance spectroscopy and charge–discharge tests indicated that (i) a structure of β-Ni(OH)2 was maintained for Ni1−xMnx(OH)2; (ii) the surface electrochemical activity of nickel hydroxide could be effectively improved by Mn substitution; (iii) capacity of Ni0.8Mn0.2(OH)2 reached 282 mA h/g and it showed an excellent cycling durability; (iv) compared to no-substituted nickel hydroxide, Ni0.8Mn0.2(OH)2 showed a decrease both in charge–discharge plateau and capacity; but with the increase of discharge rate, the difference in discharge plateau between them was smaller, and capacity of the latter exceeded the former.

► A simple ball milling process is used to prepare Mn-substituted nickel hydroxide.
► Ball milled Mn-substituted Ni(OH)2 has a structure of β-Ni(OH)2.
► The surface electrochemical activity of Ni(OH)2 is improved by Mn substitution.
► The capacity of Ni0.8Mn0.2(OH)2 reaches 282 mAh/g.
► Ni0.8Mn0.2(OH)2 has an excellent cycling durability.