Batteries manganese dioxide

K. V. Kordesch, ed.. Batteries, Manganese Dioxide, Vol. 1, Marcel Dekker, New York, 1974. 

There are approximately 250 known manganese minerals. The primary ores which typically have a Mn content >35%, usually occur as oxides or hydrated oxides, or to a lesser extent as siUcates or carbonates. Table 5 Hsts the manganese-containing minerals of economic significance (10). Battery-grade manganese dioxide ores are composed predominately of nsutite, cryptomelane, and todorokite. 

Electrolytic Manganese Dioxide. The anodic oxidation of an Mn(II) salt to manganese dioxide dates back to 1830, but the usefuhiess of electrolyticaHy prepared manganese dioxide for battery purposes was not recognized until 1918 (69). Initial use of electrolytic manganese dioxide (EAfD) for battery use was ia Japan (70) where usage continues. 

The most significant nonferrous use of manganese compounds is for primary batteries, where manganese dioxide is the principal constituent of the cathode mix. In the standard Leclanchn ceU, 2inc and ammonium chloride are mixed to form the electrolyte, a mixture of carbon and MnO forms the cathode, and 2inc acts as the anode (221). The principal ceU reaction is as foUows ... 

The cathode mix for a Leclanchn primary battery consists of 50—60% manganese dioxide ore, 5—10% acetylene black, 10—20% ammonium chloride, and 3—12% 2inc chloride. The remainder is water (see Batteries, primary cells). 

D. Glover, B. Schumm, Jr., and A. Ko2awa, eds.. Handbook of Manganese Dioxides—Battery Grade, International Battery Material Association (IBBA, Inc.), Bmnswick, Ohio, 1989. 

Fig. 1. Schematic representation of a battery system also known as an electrochemical transducer where the anode, also known as electron state 1, may be comprised of lithium, magnesium, zinc, cadmium, lead, or hydrogen, and the cathode, or electron state 11, depending on the composition of the anode, may be lead dioxide, manganese dioxide, nickel oxide, iron disulfide, oxygen, silver oxide, or iodine.

Cell Chemistry. Work on the mechanism of the carbon—2inc cell has been summari2ed (4), but the dynamics of this system are not entirely understood. The electrochemical behavior of electrolytic (FMD), chemical (CMD), and natural (NMD) manganese dioxide is slightly different. Battery-grade NMD is most commonly in the form of the mineral nsutite [12032-72-3] xMn02, which is a stmctural intergrowth of the minerals... 

Cathode Reaction. There are many different types of manganese dioxide (18), having varying activity in batteries. The only type suitable for alkaline batteries is y-Mn02, the mineral form of which is nsutite. The chemical composition of has been described (19) by the general formula... 

Performance. Alkaline manganese-dioxide batteries have relatively high energy density, as can be seen from Table 2. This results in part from the use of highly pure materials, formed into electrodes of near optimum density. Moreover, the cells are able to function well with a rather small amount of electrolyte. The result is a cell having relatively high capacity at a fairly reasonable cost. 

Water is not used in the reaction. Therefore, these cells have a very high capacity, exceeding that of zinc—manganese dioxide batteries (Table 2). 

Fig. 18. Discharge curves for miniature 2inc—silver oxide batteries (-), and 2inc—manganese dioxide batteries (—) (21).

The chemistry is the same as for alkaline manganese—dioxide batteries. The constmction features are typical of the other miniature alkaline batteries. 

The button cells that provide the energy for watches, electronic calculators, hearing aids, and pacemakers are commonly alkaline systems of the silver oxide-zinc or mercuric oxide-zinc variety. These alkaline systems provide a vei y high energy density, approximately four times greater than that of the alkaline zinc-manganese dioxide battery. 

The initial voltage of an alkaline-manganese dioxide battery is about 1,5 V. Alkaline-manganese batteries use a concentrated alkaline aqueous solution (typically in the range of 30-45 % potassium hydroxide) for electrolyte. In this concentrated electrolyte, the zinc electrode reaction proceeds, but if the concentration of the alkaline solution is low, then the zinc tends to passivate. 

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