Zinc-manganese batteries

Zinc manganese batteries consist of Mn02, a proton insertion cathode (cf. Figure 15F), and a Zn anode of the solution type. Depending on the pH of the electrolyte solution, the Zn + cations dissolve in the electrolyte (similar to the mechanism shown in Figure 15B) or precipitate as Zn(OH)2 (cf. mechanism in Figure 15C). 

Batteries are known for about 100 electrochemical systems. Today, many of them are of mere historical interest. Commercially, batteries of less than two dozens of systems are currently produced. The largest production volumes are found in just three systems primary zinc-manganese batteries (today with an alkaline electrolyte, in the past with a salt electrolyte), rechargeable lead acid batteries, and rechargeable alkaline (nickel-cadmium, nickel-iron) batteries. Batteries of these systems have been manufactured for more than a century, and until today are widely used. 

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

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 discharge of alkaline-manganese batteries comes from the electrochemical reactions at the anode and cathode. During discharge, the negative electrode material, zinc, is oxidized, forming zinc oxide at the same time, Mn02 in the positive electrode is reduced (MnOOH) ... 

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. 

Amalgamated zinc powder has been used as the negative material to prevent zinc corrosion and zinc passivation. Recently, from the viewpoint of environmental problems, mercury-free alkaline-manganese batteries were developed by using zinc powder with indium, bismuth and other additives [2-4]. Adding indium to zinc powder is the most effective way to improve the characteristics of the cells [3]. Figure 3 shows the variation in the internal impedance of the cells according to the additive content of the zinc powder. 

J K. Kordesch, W. Harer, Y. Sharma, R. Uji, K. Tomantschger, D. Freeman, Rechargeable, alkaline zinc manganese dioxide batteries, 33rd Int. Power Sources Svmp., Cherry Hill, NJ, June 13-16,1988, 440 51. 

K. Kordesch, S. Yuwei, Technology process of rechargeable alkaline zinc manganese dioxide batteries in Battery Bimonthly, 1995, 25, (Di-anchi Support Human Light Industry Research Institute). 

J. Daniel-Ivad, K. Kordesch, In-application use of rechargeable alkaline manganese diox-ide/zinc RAM batteries, Portable by Design Conference, Santa Clara, CA, March 24-27, 1997... 

From the 1960s onward, alkaline zinc-manganese dioxide batteries started to be produced. They have appreciably better electrical performance parameters (see Section 19.4.3) but do not differ from Leclanche batteries in their operating features, are produced in identical sizes, and can be used interchangeably with them. Thus, a gradual changeover occurred and phaseout of the older system is now almost complete. 

Another example for reactions with the insertion of protons is the cathodic reduction of manganese dioxide, which occnrs dnring discharge of the positive electrodes in zinc-manganese dioxide batteries. This reaction can be formulated as... 

Debatox A rotary kiln system for recycling consumer battery materials developed by Sulzer Chemtech. The system first shreds the batteries and then incinerates them. Carbon, plastics, and paper are burnt. Dioxins are destroyed in an afterburner, and mercury is condensed in a scrubber. The residual solids, containing zinc, manganese, and iron, can be recycled by standard smelters. 

Only a few of the thousands of proprosed battery systems have been commercialized. A set of criteria can be established to characterize reactions suitable for use in selecting chemical systems for commercial battery development. Very few combinations can meet all of the criteria for a general purpose power supply. The fact that two of the major battery systems introduced more than 100 years ago, lead acid (rechargeable) and zinc—manganese dioxide (primary), are still the major systems in their category is indicative of the selection process for chemical reactions that can serve the battery marketplace. 

Cadmium, along with nickel, forms a nickel-cadmium alloy used to manufacture nicad batteries that are shaped the same as regular small dry-cell batteries. However, a major difference is that the nicads can be recharged numerous times whereas the common dry cells cannot. A minor difference between the two types of cells is that nicads produce 1.4 volts, and regular carbon-zinc-manganese dioxide dry-cell batteries produce 1.5 volts. 

An application of thick-film printing technology for the fabrication of a Zn-Mn02 alkaline batteries [342] was also described. The mechanism of the capacity fade of rechargeable alkaline zinc-manganese cell was studied and discussed [343]. Zinc electrode with addition of several oxides (HgO, Sb203) for alkaline Zn-Mn02 cells [344] was also studied. 

Czerwihski and coworkers [345] reviewed the electrochemical applications of reticulated vitreous carbon (RVC). Special attention was paid to the use of RVC as an electrode support in zinc-manganese and zinc-halogen batteries. 

The manufacture of secondary batteries based on aqueous electrolytes forms a major part of the world electrochemical industry. Of this sector, the lead-acid system (and in particular SLI power sources), as described in the last chapter, is by far the most important component, but secondary alkaline cells form a significant and distinct commercial market. They are more expensive, but are particularly suited for consumer products which have relatively low capacity requirements. They are also used where good low temperature characteristics, robustness and low maintenance are important, such as in aircraft applications. Until recently the secondary alkaline industry has been dominated by the cadmium-nickel oxide ( nickel-cadmium ) cell, but two new systems are making major inroads, and may eventually displace the cadmium-nickel oxide cell - at least in the sealed cell market. These are the so-called nickel-metal hydride cell and the rechargeable zinc-manganese dioxide cell. There are also a group of important but more specialized alkaline cell systems which are in use or are under further development for traction, submarine and other applications. 

Primary alkaline cells use sodium hydroxide or potassium hydroxide as tlie electrolyte. They can be made using a variety of chemistries and physical constructions. The alkaline cells of the 1990s are mostly of the limited electrolyte, dry cell type. Most primary alkaline cells are made sing zinc as the anode material a variety of cathode materials can be used. Primary alkaline cells are commonly divided into tW o classes, based on type of construction the larger, cylindrically shaped batteries, and the miniature, button-type cells. Cylindrical alkaline batteries are mainly produced using zinc-manganese dioxide chemistry, although some cylindrical zinc-mercury oxide cells are made. 

Zinc-Manganese Dioxide Batteries. The combination of a zinc anode and manganese dioxide cathode, which is the dominant chemistry in large cylindrical alkaline cells, is used in some miniature alkaline cells as well. Overall, this type of cell does not account for a huge share of the miniature cell market. It is used in cases where an economical power source is wanted and where the devices can tolerate the sloping discharge curve shown in Figure 2. 

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