Types of Cells and Batteries

Various types of cell and battery design and construction can be used in the nickel-zinc battery system. Cells have been built in both prismatic and cylindrical designs and both vented and sealed designs. However, most current commercial applications require the use of a sealed, maintenance-free design. A typical sealed prismatic battery is shown in Fig. 31.7. This type of construction can be used for a wide range of cell sizes and is particularly suited to larger capacity batteries (e.g. greater than 10 Ampere-hours). 

The maximum charge current to be considered for a particular method of charge is determined by the ability of the hattery to accept this current on overcharge. These maximum currents differ with type of cell and battery and may even be different for various sizes of the same type. Such information is always available from the batteiy supplier. 

Average service life data for a selection of these various types of cells and batteries are listed in Table 54.2 (1.5-9V) and Table 54.3 (12-510V) for different test schedules. 

Most plant cells contain at least one membrane-limited Internal vacuole. The number and size of vacuoles depend on both the type of cell and its stage of development a single vacuole may occupy as much as 80 percent of a mature plant cell (Figure 5-24). A variety of transport proteins in the vacuolar membrane allow plant cells to accumulate and store water, ions, and nutrients (e.g., sucrose, amino acids) within vacuoles (Chapter 7). Like a lysosome, the lumen of a vacuole contains a battery of degradatlve enzymes and has an acidic pH, which is maintained by similar transport proteins in the vacuolar membrane. Thus plant vacuoles may also have a degradatlve... 

A battery consists of a number of cells connected in series. The series connection is necessary to create sufficient load voltage. Each cell has a low voltage which is peculiar to the type of cell and independent of the current and rating of the cell. The cell voltages are shown in Table 17.1. 

Apart from the improvement and scaling up of known systems such as the lead accumulator or the nickel/cadmium cell, new types of cells have also been developed. Here, rechargeable lithium batteries and nickel-systems seem to be the most promising the reason for this will be apparent from the following sections [3]. 

Secondary cells are galvanic cells that must be charged before they can be used this type of cell is normally rechargeable. The batteries used in portable computers and automobiles are secondary cells. In the charging process, an external source of electricity reverses the spontaneous cell reaction and creates a nonequilibrium mixture of reactants. After charging, the cell can again produce electricity. 

In the design of membrane-type fuel cell stacks (batteries), membrane-electrode assemblies (MEAs) are used, which consist of a sheet of membrane and of the two electrodes (positive and negative) pressed onto it from either side. 

The investigations of various types of carbon-based catalysts allow suitable air electrodes to be developed for use in the large variety of metalair cells and batteries designed in this laboratory. 

There are two types of cells electrolytic (which requires a battery or external power source) and voltaic (which requires no battery or external power source). The reaction in the diagram is voltaic and therefore spontaneous. In a voltaic cell, the anode is the negative terminal, and oxidation occurs at the anode. Remember the OIL portion of OIL RIG (Oxidation Is Losing electrons) and AN OX (ANode is where Oxidation occurs). 

A fuel stack is a series connection of fuel cells. Strictly speaking, it is fuel cell battery (cf. footnote 1). The composition and design of the fuel cell stack differ for the implementation of each type of cell. 

Lithium secondary batteries can be classified into three types, a liquid type battery using liquid electrolytes, a gel type battery using gel electrolytes mixed with polymer and liquid, and a solid type battery using polymer electrolytes. The types of separators used in different types of secondary lithium batteries are shown in Table 1. The liquid lithium-ion cell uses microporous polyolefin separators while the gel polymer lithium-ion cells either use a PVdF separator (e.g. PLION cells) or PVdF coated microporous polyolefin separators. The PLION cells use PVdF loaded with silica and plasticizer as separator. The microporous structure is formed by removing the plasticizer and then filling with liquid electrolyte. They are also characterized as plasticized electrolyte. In solid polymer lithium-ion cells, the solid electrolyte acts as both electrolyte and separator. 

A more recent use of nickel is in the manufacture of the rechargeable nickel-chrome electric cell. One of the electrodes in this type of cell (battery) is nickel (11) oxide (Ni + O — NiO). (Note When two or more cells are combined in an electrical circuit, they form a battery, but when just one is referred to, it is called a cell.) Although the electrical output of a Ni-Chrome cell is only 1.4 volts (as compared to 1.5 volts dry cells), Ni-Chrome has many uses in handheld instruments such as calculators, computers, electronic toys, and other portable electronic devices. 

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. 

Materials development and synthesis is another important dual-use type of chemistry. Developments over the past few decades include a number of elec-troitic materials and their processing, fuel cells and batteries, photoresist and semiconductor synthesis, high-performance composites (structural components) and nanocomposite materials, colloidal nanoparticle technology, solid-state lasers, and light-emitting diodes. 

Numerous other types of cells exist such as zinc-air, aluminum-air, sodium sulfur, and nickel-metal hydride (NiMH). Companies are on a continual quest to develop cells for better batteries for a wide range of applications. Each battery must be evaluated with respect to its intended use and such factors as size, cost, safety, shelf-life, charging characteristics, and voltage. As the twenty-first century unfolds, cells seem to be playing an ever-increasing role in society. Much of this is due to advances in the consumer electronics and the computer industry, but there have also been demands in numerous other areas. These include battery-powered tools, remote data collection, transportation (electric vehicles), and medicine. 

This type of cell is another variant on the basic Leclanche cell. In this case, the electrolyte is a concentrated aqueous solution of potassium hydroxide (about 30%), partly converted to potassium zincate by the addition of zinc oxide. The main advantage of alkaline manganese cells over Leclanche cells is their relatively constant capacity over a wide range of current drains and under severe service schedule conditions. Another feature of this system is that it can be the basis of a secondary battery system. The cell reaction may be written formally as... 

Some successful development of rechargeable solid state systems was achieved by using lithium intercalation cathodes, such as TiS2, which operate in exactly the same manner as in the lithium-organic cells described in Chapter 7. One example of this type of cell is provided by the battery system developed in the 1970s by P. R. Mallory and Co. (now Duracell) based on the following scheme ... 

---