Zinc-carbon batteries construction

During this transitional phase, the zinc-carbon batteries can be classified into two types, Leclanche and zinc chloride. These can, in turn, be subdivided into separate general purpose and premium battery grades, in both pasted and paper-lined constructions ... 

The zinc-carbon battery is made in many sizes and a number of designs but in two basic constructions cylindrical and flat. Similar chemical ingredients are used in both constmc-tions. 

Camacho cell — This was a - chromic acid battery with zinc anodes, and a construction that the chromic acid solutions flowed through the cathode compartment housing the inert carbon electrodes. See also - Daniell cell, - zinc, - Zn2+/Zn electrodes, - Zn2+/Zn(Hg) electrodes, - zinc-air batteries (cell), and - Leclanche cell. Ref [i] Hauck WP (1883) Die Galvanischen Batterien, Accumulatoren und Thermosaulen, 2nd edn. Hartleben s Verlag Wien... 

Chutaux cell — This was a chromic acid (carbon electrode)-zinc - battery constructed in such a way that the electrolyte solutions could flow along the electrodes to reduce concentration polarization. 

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. 

Because the introduction of lithium power sources to the electronics industry is so recent, many potential users are not aware that lithium batteries are not all alike. Lithium is only the first name of any lithium power source. Just as there are many zinc batteries available (zinc-carbon, zinc-silver cxide, zinc-mercuric oxide) there are many varieties of lithium system, each with its own peculiar internal chemistry and construction. Several of these systems are briefly described below. 

Cylindrical alkaline manganese batteries have an inverted construction compared with the familiar Leclanch carbon-zinc battery construction. A typical construction of this type of battery is shown in Figure 21.1. 

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"... 

FIGURE 10.3 Construction of the carbon-zinc cells. The zinc chloride and Leclanche have the same construction except for the seal. The zinc chloride has a plastic-compression seal while the Leclanche has a poured hot bituminous seal instead of the plastic-compression seal shown. (Courtesy of Eveready Battery Co., St Louis, MO. With permission.)... 

Bunsen s chromic acid battery -> Bunsen constructed a -> chromic acid battery with zinc anodes for the purpose of producing electric sparks for spectral analysis [i]. The electrodes (carbon and zinc) could be immersed in... 

As his research advanced to the studies of gases and alkali metals, Bunsen recognized the importance of developing new methods to analyze and identify chemical substances. The importance of quantitative analysis was realized in the late eighteenth century. Chemists needed to probe further into a substance s composition in order to help explain the physical world. Bunsen recognized this need and worked to develop new instruments for this purpose. For example, he invented new types of galvanic and carbon-zinc electrochemical cells, or batteries, to isolate barium and sodium. He also constructed a new type of ice calorimeter that measured the volume, rather than the mass, of melted water. This allowed Brmsen to measure a metal s specific heat in order to find its atomic weight. 

The following cross-sectional drawings provide a quick comparison as to how these considerations influence the final battery design and electrode configurations. Figures 1, 2, and 3 show the cross sections of the three most common cylindrical ceU designs. Figure 1 is referred to as a carbon zinc construction where the center carbon electrode, which is used as a cathode current collector and gas vent, is most evident, and... 

Primary Battery Design, Fig. 1 (Carbon zinc) Zn can/anode with Mn02 cathode and a porous carbon rod current collectin and vent. Low rate - oldest construction... 

Construction of the zinc chloride cylindrical battery (Fig. 8.3) differs from that of the Leclanchd battery in that it usually possesses a resealable, venting seal. The carbon rod serving as the current collector is sealed with wax to plug any vent paths (necessary for... 

The flat cell is illustrated in Fig. 8.5. In this construction, a duplex electrode is formed by coating a zinc plate with either a carbon-filled conductive paint or laminating it to a carbon-filled conductive plastic film. Either coating provides electrical contact to the zinc anode, isolates the zinc from the cathode of the next cell, and performs the function of cathode collector. The collector function is the same as that performed by the carbon rod in cylindrical cells. When the conductive paint method is used, an adhesive must be placed onto the painted side of the zinc prior to assembly to effectively seal the painted surface directly to the vinyl band to encapsulate the cell. No expansion chamber or carbon rod is used as in the cylindrical cell. The use of conductive polyisobutylene film laminated to the zinc instead of the conductive paint and adhesive usually results in improved sealing to the vinyl however, the film typically occupies more volume than the paint and adhesive design. These methods of construction readily lend themselves to the assembly of multi-cell batteries. 

Mercury batteries have an appreciably higher energy-to-weight ratio than carbon-zinc batteries, resulting from the high energy density of the materials used in their construction. Thus mercury batteries are only one-third the size of conventional dry batteries of the same capacity. 

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