Cells and Alkaline Batteries

The most common batteries, dry cells and alkaline batteries, are those used in flashlights, toys, and certain portable electronics such as CD players. The two are similar in appearance, but differ in the spontaneous chemical reaction responsible for producing a voltage. Although the reactions that take place in these batteries are somewhat complex, the reactions shown here approximate the overall processes. 

Alkaline batteries are more expensive than dry cells and offer superior performance and shelf life. 

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Mn02 has a number of uses in chemical processes as an oxidizing agent, and it is also used in dry cell and alkaline batteries. In both cases the anode is made of zinc. The anode reaction (oxidation) and cathode reaction (reduction) are as follows for an alkaline cell ... 

Unlike dry cells and alkaline batteries, the lead storage battery is rechargeable. Recharging the battery means reversing the normal electrochemical reaction by applying an external voltage at the cathode and the anode. (This kind of process is called electrolysis, which we discuss in Section 19.7.)... 

Practically every battery system uses carbon in one form or another. The purity, morphology and physical form are very important factors in its effective use in all these applications. Its use in lithium-ion batteries (Li-Ion), fuel cells and other battery systems has been reviewed previously [1 -8]. Two recent applications in alkaline cells and Li-Ion cells will be discussed in more detail. Table 1 contains a partial listing of the use of carbon materials in batteries that stretch across a wide spectrum of battery technologies and materials. Materials stretch from bituminous materials used to seal carbon-zinc and lead acid batteries to synthetic graphites used as active materials in lithium ion cells. 

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. 

The worst drawback of the Ni/Cd battery is its cost, but progress has been made in recent years and Ni/Cd batteries are gradually replacing Leclanche cells and alkaline Zn/MnO primary batteries in many simple applications, such as mechanical toys and even flashlights. This is a very welcome development from the ecological point of view, since each Ni/Cd battery can replace hundreds of primary cells before it is thrown out. 

A battery cell consists of chemical compoimds, internal conduaors, positive and n ative connections, and the casii. Examples of cells include sizes N, AA, AAA, C, and D. A cell that caimot be recharged is called a primary cell An alkaline battery is an example of a primary cell. On the other hand, a secondary cell is a cell that can be recharged. The recharging is accomplished by reversing the current flow finm the positive to the negative areas. Lead add cells in your car battery and nickel-cadmium (NiCd), and nickel-metal hydride (NiMH) cells are examples of secondary cells. The NiCd batteries are some of the most common rechargeable... 

Secondary Cells and Batteries Containing Alkaline or Other Non-acid Electrolytes - Safety Requirements for Portable Sealed Secondary Cells, and for Batteries Made from Them, for Use in Portable Applications, lEC 62133 Edition 1.0. 

Fig. 5 Comparison of AA Li-FeS2 cells and alkaline cells at low temperature (courtesy of Energizer Battery Manufacturing Inc.)...

The standard cell uses MnOj as the cathode with ammonium chloride as the electrolyte, and this cell is known as a Zn-Cl or an alkaline battery. The C-Zn batteries are not satisfactory for electrical devices, such as tape recorders and disc players, high-resolution automatic cameras, flash units, and certain toys, because they are not able to provide electrical energy needed for satisfactory and reliable operation. Because of power hmitations of C-Zn batteries, alkaline batteries are widely used by low-power devices. Typical characteristics of C-Zn and alkaline batteries are summarized in Table 1.12. 

Uses. Nickel nitrate is an intermediate in the manufacture of nickel catalysts, especially those that are sensitive to sulfur and therefore preclude the use of the less expensive nickel sulfate. Nickel nitrate also is an intermediate in loading active mass in nickel—alkaline batteries of the sintered plate type (see Batteries, SECONDARY cells). Typically, hot nickel nitrate symp is impregnated in the porous sintered nickel positive plates. Subsequendy, the plates are soaked in potassium hydroxide solution, whereupon nickel hydroxide [12054-48-7] precipitates within the pores of the plate. 

Cylindrical alkaline cells are made in only a few standard si2es and have only one important chemistry. In contrast, miniature alkaline cells are made in a large number of different si2es, using many different chemical systems. Whereas the cylindrical alkaline batteries are multipurpose batteries, used for a wide variety of devices under a variety of discharge conditions, miniature alkaline batteries are highly speciali2ed, with the cathode material, separator type, and electrolyte all chosen to match the particular appHcation. 

The potassium hydroxide electrolyte used in alkaline batteries is a corrosive hazardous chemical. It is a poison and if ingested attacks the throat and stomach linings. Immediate medical attention is required. It slowly attacks skin if not rapidly washed away. Extreme care should be taken to avoid eye contact that can result in severe bums and blindness. Protective clothing and face shields or goggles should be worn when filling cells with water or electrolyte and performing other maintenance on vented batteries. 

Zinc/carbon and alkaline/manganese cells are primary battery systems lead, nickel/cadmium, and nickel/metal hydride accumulators are secondary batteries with aqueous electrolyte solutions. Their per-... 

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