Secondary battery systems

Table 3. Comparison of primary and secondary battery systems...

Nickel—hydrogen batteries offer long cycle life that exceeds that of other maintenance-free secondary battery systems and accordingly makes it suitable for many space applications. Three types of separator materials have been used for aerospace Ni—H2 cells— asbestos (fuel-cell-grade asbestos paper), Zircar (untreated knit ZYK-15 Zircar cloth),and nylon. 

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... 

Fig. 9.18 Schematic diagram of a zinc-air secondary battery system...

As the book has been written for the non-specialist, the theoretical background to the basic processes involved in cell operation is described in some detail in preference to a more thorough series of comparisons of the characteristics and performance of competing systems. We have excluded any discussion on the very closely related field of fuel cells since a number of accounts of this topic have been published recently. It has been our intention to describe and characterize most of the established and emerging primary and secondary battery systems which are of current commercial or theoretical interest. Research into novel power sources may shortly lead to the major breakthroughs necessary before electric vehicles become a major component of the transportation system, and... 

Tables 1 and 2 contain characteristics of various primary and secondary battery systems, respectively. Table 3 contains performance parameters for promising rechargeable battery systems in various stages of research and commercial development.

FIGURE 13 Ragone plot. Acceptable automobile performance requires the specific power and specific energy shown in the upper right corner of the plot. Several secondary battery systems can meet these technical objectives. 

Recently Osaka et al [260] studied a lithium/ polypyrrole secondary battery system using PEO-LiC104 as a solid polymer electrolyte. The battery showed fairly high coulombic efficiency of about 95% with an output voltage of 3.0 V and performed very well for 1400 charge-discharge cycles after initial 100 scans required to reach optimum value. However, efficiency... 

Osaka, T., Momma, T., Nishimura, K. Kakuda, I., and Ishii, T., Application of solid polymer electrolyte to lithium/polypyrrole secondary battery system, J. Electrochem. Soc., 141, 1994-1998 (1994). 

Ever since the possibility of fabricating a practical nonaqueous Li-air battery as reported by Abraham et al. a new renewed interest has been triggered by world battery community to bring back lithium s true advantage in the form of Li-air secondary battery system. ... 

Table 1.1 Thermodynamic data, electrodes, electrolyte, cell reaction, equilibrium cell voltage, and specific energy of some customary primary-and secondary-battery systems. The theoretical specific energy, listed in Column 8 results from division of AG by the weight of the reacting components. The difference between these values and those observed in practice (Column 9) is caused by kinetic parameters.

Also secondary battery systems exhibit a broad range of different rates of selfdischarge. Their values, however, are based on a 1-month period in contrast to primary systems (1-year period). Depending on system and construction typical values vary between 2% and 30% per month at ambient temperature. For the lead-acid system the values vary between 2% and 20% per month depending on antimony content and age. The lithium-ion system offers about 5% to 10% per month. Values in the range of 20% to 30% per month are observed for the nickel cadmium and the nickel metal hydride system. 

Table 6.2 Nominal voltage of commercial secondary battery systems.

Table 4.11a is a list of organizations working on safety standards and the safety standards they prepared that cover various primary and secondary battery systems. 

As with the primary battery systems, significant performance improvements have been made with the older secondary battery systems, and a number of newer types, such as the silver-zinc, the nickel-zinc, nickel-hydrogen, and lithium ion batteries, and the high-temperature system, have been introduced into commercial use or are under advanced development. Much of the development work on new systems has been supported by the need for high-performance batteries for portable consumer electronic applications and electric vehicles. Figure 22.1 illustrates the advances achieved in and the projections of the performance of rechargeable batteries for portable applications. 

COMPARISON OF PERFORMANCE CHARACTERISTICS FOR SECONDARY BATTERY SYSTEMS... 

The characteristics of the major secondary systems are summarized in Table 22.3. This table is supplemented by Table 1.2, which lists several theoretical and practical electrical characteristics of these secondary battery systems. A graphic comparison of the theoretical and practical performances of various battery systems is given in Fig. 3.3. This shows that up to only about 20 to 30% of the theoretical capacity of a battery system is attained under practical conditions as a result of design and the discharge requirements. 

A qualitative comparison of the various secondary battery systems is presented in Table 22.4. The different ratings given to the various designs of the same electrochemical system are an indication of the effects of the design on the performance characteristics of a battery. 

TABLE 22.3 Characteristics of the Major Secondary Battery Systems... 

FIGURE 22.2 Discharge profiles of conventional secondary battery systems and rechargeable lithium ion battery at approximately C/5 discharge rate. 

FIGURE 22.3 Comparison of performance of secondary battery systems at 20°C. 

FIGURE 22.6 Capacity retention of secondary battery systems. 

The cycle life and calendar life of the different secondary battery systems are also listed in Table 22.3. Again, these data are approximate because specific performance is dependent on the particular design and the conditions under which the battery is used. The depth of discharge (DOD), for example, as illustrated in Fig. 22.7, and the charging regime strongly influences the battery s life." ... 

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