Cadmium-free battery

Nowadays, such hydride electrodes are used widely to make alkaline storage batteries which in their design are similar to Ni-Cd batteries but exhibit a considerably higher capacity than these. These two types of storage battery are interchangeable, since the potential of the hydride electrode is similar to that of the cadmium electrode. The metal alloys used to prepare the hydride electrodes are multicomponent alloys, usually with a high content of rare-earth elements. These cadmium-free batteries are regarded as environmentally preferable. 

Nickel-cadmium rechargeable batteries are being researched. Alternatives such as cadmium-free nickel and nickel hydride systems are also being researched, but nickel-cadmium batteries are unlikely to be totally replaced. Nickel-cadmium batteries can be reprocessed to reclaim the nickel. However, currently, approximately 80% of all nickel-cadmium batteries are permanently sealed in appliances. Changing regulations may result in easier access to these nickel-cadmium batteries for recycling. 

The metal hydride electrode has a higher energy density than the cadmium electrode. Therefore the amount of the negative electrode used in the nickel-metal hydride cell can be less than that used in the nickel-cadmium cell. This allows for a larger volume for the positive electrode, which results in a higher capacity or longer service life for the metal hydride battery. Furthermore, as the nickel-metal hydride battery is free of cadmium, it is considered more environmentally friendly than the nickel-cadmium battery and may reduce the problems associated with the disposal of rechargeable nickel batteries. 

Shredded circuit boards. Circuit boards are metal boards that hold computer chips, thermostats, batteries, and other electronic components. Circuit boards can be found in computers, televisions, radios, and other electronic equipment. When this equipment is thrown away, these boards can be removed and recycled. Whole circuit boards meet the definition of scrap metal, and are therefore exempt from hazardous waste regulation when recycled. On the other hand, some recycling processes involve shredding the board. Such shredded boards do not meet the exclusion for recycled scrap metal. In order to facilitate the recycling of such materials, U.S. EPA excluded recycled shredded circuit boards from the definition of solid waste, provided that they are stored in containers sufficient to prevent release to the environment, and are free of potentially dangerous components, such as mercury switches, mercury relays, nickel-cadmium batteries, and lithium batteries. 

The iron-nickel oxide alkaline battery system has many features in common with the nickel-cadmium system discussed above. It was first developed by Edison in the USA at the turn of the century and was patented in the same year as Jungner s first nickel-cadmium US patent, 1901. Iron can be regarded as a favourable active battery material because of its low cost, high theoretical specific capacity (twice that of cadmium) and non-toxic, pollution-free characteristics. However, because its reduction potential is below that of hydrogen, and since hydrogen overvoltage is low on iron, charge retention is poor and efficiency is low. 

Bemdt, D. Mainienance-Free Batteries Lead-Acid, Nickel/Cadmium, Nickel/Metal Hydride. John Wiley Sons. Inc.. New York, NY. 1997. 

Refs. [i] Linden D, Reddy TB (eds) (2001) Handbook of batteries, 3rd edn. McGraw-Hill [ii] BerndtD (ed) (2003) Maintenance-free batteries lead-acid, nickel/cadmium, nickel/hydride - A handbook of battery technology (Electronic electrical engineering research studies power sources technology). Research Studies Press... 

Maintenance-free battery— A rechargeable - battery that does not require replenishing of water during its service life. Usually the term refers to maintenance-free -> lead-acid and sealed nickel-cadmium batteries, which, in contrary to the conventional ones, are designed to suppress water loss due to -> electrolysis (overcharging) and evaporation. 

Starved electrolyte battery — A -> battery with minimum amount of -> electrolyte. The electrolyte in starved electrolyte cells or batteries exists in the porous structure of the - electrodes and absorbed in the separator, so it contains little or no free fluid electrolytic solution. This type of batteries is used in certain constructions of sealed - lead-acid and -> nickel-cadmium batteries that rely on gas diffusion and recombination on the electrodes during charging or overcharging in order to maintain maintenance-free conditions, and to suppress pressure buildup. Starved electrolyte batteries benefit from larger - energy density due to the reduced amount of electrolyte. This design may suffer from poor heat dissipation compared with -> flooded batteries, thus for high power applications this point has to be taken into account. 

The basis for the performance of the alloy in VRLA batteries is corrosion of the lead-cadmium-antimony alloy to produce antimony in the corrosion layer of the positive grid, which thus eliminates the antimony-free eifect of pure lead or lead-calcium alloys. During corrosion, small amounts of antimony and cadmium present in the lead matrix are introduced into the corrosion product and thereby dope it with antimony and cadmium oxides. The antimony and cadmium give excellent conductivity through the corrosion product. The major component of the alloy, the CdSb intermetallic alloy, is not significantly oxidized upon float service, but may become oxidized in cycling service. 

The designer never carried out tests on an industrial scale to confirm his theories only the powder, 50% of the weight of the battery, was to be treated. The other fractions were free from cadmium and so could be sold as they were. 

Accurate sorting relies on the identification of a number of different properties of a battery. These include the physical size and shape, the weight, the electromagnet properties and any surface identifiers such as colour or unique markings. These properties can be analysed in a number of different combinations in order to sort batteries into nickel cadmium, nickel metal hydride, lithium, lead acid, mercuric oxide, alkaline and zinc carbon batteries. Due to an voluntary marking initiative introduced by the european battery industry, it is now also possible to separate the alkaline and zinc carbon cells further into mercury free and mercury containing streams. 

Typical environmentally regulated substances are arsenic, cadmium, mercury, and lead. Presently, there are few products including mercury. Some electronic devices include arsenic or cadmium, and are used in a computer and so on. Lead is used in the battery of a car, and its alloys are used as solders. In addition, it is included in polyvinylchloride (PVC) cables as a stabilizer. The battery has been treated appropriately. The solder was replaced by a lead-free solder after the RoHS directive. However, a lead-free solder includes lead below 1000 (mass) ppm. The quantity of lead in PVC cables has been decreased. The consumption of the environmentally regulated material seems to decrease, but the discarded products may be the products produced before the enactment of the regulations. 

Improvements in the development of electronics have allowed devices more accurate and easier for the user (Figure 5.10). These devices need only the battery voltage for indication, but show on a display the residual capacity, in percentage, of the nominal capacity and the remaining operation. The adjustment follows the individual characteristics of lead-acid batteries (low-maintenance or maintenance-free) or of nickel-cadmium batteries. Automatic switch-off breaks the operation of the lifting device of a forklift truck when there is danger for a deep discharge of the... 

D Berndt. Maintenance Free Batteries Lead Acid Nickel/Cadmium Nickel/Metal Hydride. 2nd ed. Taunton, England Research Studies Press, 1997. 

After the approaches in the German Federal Republic to a free agreement between manufacturers and traders of conventional batteries to minimize the problems of the poisonous metals mercury and cadmium, we consequently have to talk about lithium batteries, too. This will become difficult, because the large variety of different lithium battery systems hinders a quick and simple analysis of the battery scrap and an assessment of the related risks. This might be difficult to carry out at least for local environmental authorities. 

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