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Ball-milling of Composite Powder - Cathode Production for Alkaline Batteries

Composite powder for the use in cathode of alkaline zinc-manganese dioxide batteries was prepared in a binderless way. Specifically speaking, it involved a ball-milling process using a milling agent of special shape and the composite powder of electrolytic manganese dioxide and expanded graphite formed under certain conditions. Powder characteristics such as particle size distribution and particle morphology were investigated before and after the composite process. In addition, resistivity and density were measured and calculated after the composite powder was compressed into tablets. The result showed that both the examined ball-milling parameters of rotation velocity and treatment time had a huge influence on the composite effect and that 46.7 rpm of rotation velocity and 45min of treatment time were an optimal set of ball-milling parameters in the present study. It has also been discussed that when compared with other similar studies the present result is superior but still has much room for improvement.

1 Introduction
The large-scale use of small electronic devices and other equipment in our daily life entails huge consumption of primary batteries. Alkaline Zn-MnO2 primary batteries, which consist of a MnO2 cathode and a Zn anode, are dominant in the primary batteries market [1]. For the production of cathode materials in commercial alkaline Zn-MnO2 batteries, electrolytic MnO2 (EMO) and graphite, which serve as electrochemically active material and conductive material respectively, are mixed, granulated, shaped and dried in a wet process in which the use of binder is imperative [2]. Although this method has been used up to now as the standard, it incurs several problems such as high costs, environmental pollution and inefficient utilization of cathode active material, namely EMO. In order to solve the above-mentioned problems, thereby increasing the utilization of EMO cathode material, eliminating the necessity of using a binder and improving the performance of alkaline Zn-MnO2 primary batteries, a novel dry process should be devised and explored in which particles of EMO are encapsulated by particles of graphite and the resultant composite particles can directly be used as the cathode. Few if any studies have been conducted in this specific direction. Terashita et al. [3] investigated the use of a high-performance planetary mill to produce a composite of EMO and graphite particles and it was shown that higher amount of EMO and lower electric resistance were realized by the binderless dry process. . .