Two Types of Batteries

These batteries are designed to be reehaiged and used multiple times. That is, they ean have their chemical reactions reversed by supplying electrical energy to the cell, restoring their original composition. Thus these are also called rechargeable batteries. Cells of this type include nickel-cadmimn (NiCd), nickel-zinc (NiZn), and lithium-ion (Li-ion) cells. 

---

Two types of batteries having immobilized electroltye systems are also made. Tliey are most common m consumer appHcations, but their use m mdustrial and SLI appheations is mcreasmg. Both types hav e low maintenance requhements and usually can be operated m any position. Tliey are sometimes called valv e regulated or recombmant batteries because they are equipped with a one-way pressure rehef v ent and nomially operate m a sealed condition with an oxygen recombhiation cycle to reduce water loss. 

Batteries, both primary and secondary, have become very big business indeed, which moreover is growing rapidly. Salkind (1998) in a concise overview of the entire domain of battery types and technologies, estimates that in 1996, the world market in the two types of battery combined totalled ss 33 billion dollars, and that the ratio of secondary to primary battery sales is steadily edging upwards. In spite of its poor charge density per unit mass, the lead-acid battery still accounts for more than a quarter of the total, because it costs so much less than its rivals and lasts well. 

Figure 65 shows commercialized LiCo02-natural graphite cells and Table 18 shows the specification of these batteries. There are two types of batteries cylindrical and prismatic. The cylindrical-type battery in Fig. 65 is called 18650 because its diameter is 18 mm and its length is 65 mm. 

Electronic Time Fuze. Development of an electronic time fuze which would be substantially more accurate than exisitng time fuzes is described in the report of Texas Instruments, Inc (Ref). A programmable digital circuit is driven by. an oscillator based on a Picatinny Arsenal design. As power source, two types of battery, a silver-zinc primary battery and a reserve battery which uses ammonia as the electrolyte, were tried. A detailed manufacturing plan is included as an appendix... 

The manufacturers of these two types of batteries do not distinguish them by service life tests. In fact, similar mAh output is obtained at loads lighter than the 500 hr rate. The industry uses pulse CCV tests to differentiate the higher rate version from the low rate version. Different producers use different CCV loads, durations, and minimum voltages. For example, at Rayovac, the following tests are used... 

Lithium Molybdenum Disulfide LiiMoS Batteries. The Li/MoS2 system was the first rechargeable lithium battery to be manufactured when it was introduced in the mid-1980s in a cylindrical AA-size. The ceU used thin lithium metal anodes (125 /xm), with a stoichiometric excess of about three times, and M0S2 on a thin aluminum foil (150 /u.m) for the cathode. A spirally wound construction, as illustrated in Fig. 34.13, was used. The electrolyte was IM LiAsF(j dissolved in a 50 50 mixture of propylene carbonate and ethylene carbonate. Two types of batteries were manufactured. Table 34.12 describes the more advanced of the two. 

Miniature applications have become more important in recent years with the general aeeeptance of the behind-the-ear hearing-aid and the advent of the electronic watch. High energy density per unit volume is the prime requirement for a battery in these products. The mercuric oxide-zinc, silver oxide-zinc, zinc-air and lithium-based systems appear to be likely contenders for this market. Although the last two types of battery have been produced in sizes suitable for miniature applications, they are not widely available in this format. These systems will therefore be discussed later in their usual cylindrical form, and the conclusions drawn then may explain the difficulties that have prevented their wide acceptance. 

In addition to these two types of battery, there arc several others which, because of their higher cost, are not used as extensively, but are nevertheless cf direct interest in particular fields. This is because of their outstanding performance characteristics in certain specialized applications, e.g. silver—zinc and silver—cadmium batteries. 

---