Alkaline cell construction

Figure 2 is a typical alkaline cell construction which uses the same electrochemical couple as the carbon zinc cell. However, in this case the zinc is a powder, in the center of the cell, and the container is made of an inactive material, such as steel. Like carbon zinc cells, the cathode is manganese dioxide. The electrolyte is based on potassium hydroxide (or in some coin cells sodium hydroxide), which explains the use of the term alkaline to describe these cells. 

Figure 1. Cell construction of an alkaline-manganese battery...

The cell construction of an alkaline-manganese battery is shown in Fig. 1. The steel can serves as a current collector for... 

Alkaline batteries were introduced in the early 1960s they last two to five times longer than Zn-carbon cells on continuous discharge and command two or three times the price in the USA (far more in Europe and the East). Alkaline cells became a necessary invention and they succeeded as a result of the requirements of the electronic devices. The essential improvement was the change from ammonium chloride and/or zinc chloride electrolyte to alkaline (KOH) electrolyte, the steel can construction, the outside cathode, and the zinc powder (large surface) anode. A main low-cost feature is that they use pressed cathodes and do not need to follow "jellyroll"... 

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. 

Cylindrical alkaline cells are zinc-manganese dioxide cells having an alkaline electrolyte, which arc constructed in the standard cylindrical sizes, R2D D, R14 C . R6 AA , ROT AAA, as well as a few other less common sizes, llley can be used in the same types of devices as ordinary Leclanchd and zinc chloride cells. Moreover, die high level of performance makes them ideally suited for applications such as toys, audio devices, and cameras. 

In the cells constructed by Garuti2 and Pompili prior to 1899 lead electrodes were employed, and the electrolyte was sulphuric acid solution which was contained in a lead-lined wooden tank, but this was abandoned ultimately for iron construction and an alkaline electrolyte. 

There are two main cell constructions in consumer and industrial markets for alkaline Zn/Mn02 batteries. The most common construction is the cylindrical cell, which is most widely being used for various industrial and consumer applications and it is generally categorized as D, C, AA, AAA sizes. Fig. 2 shows the cross-section of the typical construction of cylindrical cells. It is noted that the cylindrical steel can functions as both cathode current collector and the cell container. The inner surface of the can is usually plated with Ni or treated with conductive carbon coatings in order to improve contact with cathode mixture. On the other... 

Fig. 2 Typical cell construction of the cylindrical alkaline cell. (From Ref...

Since 1987 the development emphasis was shifted to the AA size cell which represents over 50 % of the consumer market. Figure 16 shows that the 1992 cell design has become very similar to the one of primary alkaline cells. Most noticeable is a simplification of the cell construction. Both mechanical cathode confinement and the complicated current collector design were abandoned [38]. 

Alkaline cells use the same zinc-manganese dioxide couple as Leclanche cells. However, the ammonium chloride electrolyte is replaced with a solution of about 30 wt% potassium hydroxide (KOH) to improve ionic conductivity. The ceU reactions are identical to those above, but the battery construction is rather different (Figure 9.7). The negative material is zinc powder, and the anode (negative terminal) is a brass pin. The positive component is a mixture of Mn02 and carbon powder that surrounds the anode. A porous cylindrical barrier separates these components. The positive terminal (cathode) is the container, which is a nickel-plated steel can. 

Alkaline cells are available worldwide in a variety of sizes and shapes. The term alkaline ceU is used to describe the specific cell containing zinc aUoy powder anode, nanostmc-tured electrolytic manganese dioxide cathode, and concentrated potassium hydroxide (KOH) electrolyte. The construction of the D-size cell is given in Fig. 1 and is typical of the constmc-tions of all alkaline cylindrical cells from the... 

The superior performance of the alkaline cell is the result of the use of electrolytic manganese dioxide, high-surface-area zinc powder, as well as the high conductivity alkaline electrolyte in the cell construction. The higher performance of the alkaline cell carries over to better low-temperature performance, as well. 

Alkaline Primary Cells, Fig. 7 Cutaway view of the alkaline Zn-Mn02 coin cell construction (Courtesy of Duracell)... 

High specific energy and energy density which allows the construction of primary cells that are two to five times better than conventional alkaline cells from an energy standpoint. 

Figure 20.2 Construction of the Leclanche cell and the alkaline cell.

Rechargeable secondary alkaline cells are connected with two famous names Thomas A. Edison and Valdemar Jungner. While Edison was the inventor of the nickeliron battery, Jungner tried to improve the secondary alkaline battery by using cadmium for the negative electrode. The different constructions are described in detail in Chapter 1, Sec. 1.8.2, and Chapter 7, Sec. 7.3. 

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