Batteries, nickel-cadmium

Hydrogen-storage alloys (18,19) are commercially available from several companies in the United States, Japan, and Europe. A commercial use has been developed in rechargeable nickel—metal hydride batteries which are superior to nickel—cadmium batteries by virtue of improved capacity and elimination of the toxic metal cadmium (see BATTERIES, SECONDARYCELLS-ALKALINe). Other uses are expected to develop in nonpolluting internal combustion engines and fuel cells (qv), heat pumps and refrigerators, and electric utility peak-load shaving. 

Spontaneous low resistance internal short circuits can develop in silver—zinc and nickel—cadmium batteries. In high capacity cells heat generated by such short circuits can result in electrolyte boiling, cell case melting, and cell fires. Therefore cells that exhibit high resistance internal short circuits should not continue to be used. Excessive overcharge that can lead to dry out and short circuits should be avoided. 

Because of increasing environmental concerns, the disposal of all batteries is being reviewed (70—76). Traditionally silver batteries were reclaimed for the silver metal and all other alkaline batteries were disposed of in landfills or incinerators. Some aircraft and industrial nickel —cadmium batteries are rebuilt to utilize the valuable components. 

To reduce or eliminate the scattering of cadmium in the environment, the disposal of nickel —cadmium batteries is under study. Already a large share of industrial batteries are being reclaimed for the value of their materials. Voluntary battery collection and reclaiming efforts are under way in both Europe and Japan. However the collection of small batteries is not without difficulties. Consideration is being given to deposit approaches to motivate battery returns for collection and reclamation. 

In 1988, cadmium metal production in the United States increased significantly and imports decreased, but exports increased. Dramatic increases in cadmium prices in 1988 were attributed to the tight supply of cadmium worldwide, heavy speculative trading, and the large quantities of cadmium being purchased by the nickel—cadmium battery industry, particularly in Japan. About 30 countries are cadmium producers, led by Russia, Japan, the United States, Canada, Belgium, Germany, and Mexico, which cumulatively represented 64% of the 1988 reported world cadmium production of 19,773 metric tons. 

The composition of EAF dust can vary greatly, depending on scrap composition and furnace additives. EAF dust usually has a zinc content of more than 15%, with a range of 5 to 35%. Other metals present in EAF dust include lead (2-7%), cadmium (generally 0.1-0.2% but can be up to 2.5% where stainless steel cases of nickel-cadmium batteries are melted), chromium (up to 15%), and nickel (up to 4%). 

Nickel-cadmium and nickel-iron are prime examples of rechargeable (secondary) batteries, invented in 1901 by Waldemar Jungner and Edison, respectively. In the 1920s and 1930s, such batteries powered radios prior to rural clectrificadnn. The sealed nickel-cadmium battery is now the most widely used battery in consumer products. 

The Edison dry cell nickel/cadmium battery and the Jungers nickel/iron cell are developed work on these endeavors lasts until 1905. 

Battery types are either lead-acid or nickel-cadmium cells. Lead-acid types have been used for a long time and, when correctly maintained, have a working life of 25 years. Nickel-cadmium batteries offer the same working life as lead-acid but are smaller in weight and volume, generally with a higher initial capital cost. Loads applied to D.C. systems can be categorized into three types ... 

In a nickel-cadmium battery (Nicad), cadmium is oxidized to Cd(OH)2 at the anode, while Ni203 is reduced to Ni(OH)2 at the cathode. A portable CD player uses 0.175 amp of current. How many grams of Cd and Ni203 are consumed when the CD player is used for an hour and a half ... 

The nickel-cadmium battery [6] has a positive electrode made of nickel hydrox-... 

The nickel-cadmium battery was invented by Jungner in 1899. The battery used nickel hydroxide for the positive electrode, cadmium hydroxide for the negative electrode, and an alkaline solution for the electrolyte. Jungner s nickel-cadmium battery has undergone various forms of the development using improved materials and manufacturing processes to achieve a superior level of performance. 

Focusing on the concept of the completely sealed system, the Sanyo Electric Co. developed sealed-type nickel-cadmium batteries in 1961. This type of battery enjoys a wide application range that is still expanding a large variety of nickel-cadmium batteries has been developed to meet user needs ranging from low-current uses like emergency power sources and semiconductor memories to high-power applications such as cordless drills. 

The significant features of nickel-cadmium batteries can be summarized as follows ... 

For many years, sintered-nickel electrodes have been used as the positive electrodes for sealed-type nickel-cadmium batteries. With an increase in the demand for high energy density, this type of elec-... 

As mentioned above, nickel-cadmium batteries have excellent characteristics and... 

Nickel-metal hydride batteries contain a nickel electrode similar to that used in nickel-cadmium batteries as the positive... 

Figure 20 shows the charge-discharge characteristics of the AA-size nickel-metal hydride battery in comparison with the nickel-cadmium battery produced by Sanyo Electric. Its capacity density is 1.5 to 1.8 higher than that of nickel-cadmium batteries. 

The discharge voltage of nickel-metal hydride batteries is almost the same as that of nickel-cadmium batteries. 

Engineering Handbook of Sealed Type Nickel-Cadmium Batteries, Sanyo Electric Co., Ltd., Osaka, 1988. 

For alkaline storage batteries requirements are often demanded exceeding by far those for lead storage batteries. The reason is that the suitable materials for the positive electrode are very expensive (silver oxide, nickel hydroxide) and thus the use of these storage batteries is only justified where requirements as to weight, number of cycles, or temperature range prohibit other solutions. Besides a few standardized versions — mainly for nickel-cadmium batteries — this has led to the existence of a large diversity of constructions for special applications [4-6, 108, 109],... 

One version of the microporous, filled polyethylene separator ( PowerSep ) [113], which is so successful in the lead-acid battery, is also being tested in nickel-cadmium batteries. This separator is manu-... 

---