NiMH rechargeable batteries

Outlook for rare earth based metal hydrides and NiMH rechargeable batteries... 

L. Y. Zhang, Rare Earth-Based Metal Hydrides and NiMH Rechargeable Batteries, Rare Earths Science Technology Applications 3rd Symp. Orlando, Ha., Feb. 1997 Minerals, Meteils Materials Soc. 

The rechargeable battery (NiCd, NiMH, and lithium-ion) market for 2003 for portable electronics was around 5.24 billion, around 20% more then 2002. The lithium-ion battery market was around 3.8 billion ( 73%). They are now used in more than 90% of cellphones, camcorders, and portable computers, worldwide, and have also been adopted in power tools recently. 

The world s rechargeable battery market is shown below. The projected growth rate of NiMH from 1994 to 2000 is shown below. 

The mass of lithium ion batteries allows the automotive chemist and design engineers to decrease the mass of the overall vehicle as well as increase the performance of the vehicle. They are much lighter than other rechargeable battery designs. Lithium ions are also a wise choice for automotive use because self-discharge is very low (5% per month vs. 30% for nickel-metal hydride [NiMH] batteries). 

In the field of portable rechargeable batteries for such electronic devices, as cellular phones, personal computers and video cameras, many changes occurred in their respective markets. For over 30 years, NiCd batteries have mainly been used as the power source, but NiMH and lithium ion batteries were developed in the early 1990 s and, since then, their demand has rapidly increased. 

Table 3.5 shows the metal composition of rechargeable batteries. NiCd batteries contain such metals as Cd, Ni and Fe which are recyclable (80% of battery weight). NiMH batteries contain recyclable Ni, Co, Fe and rare metals (85%). Finally, Li-ion batteries mostly contain Co, Fe, Al, Cu and Li (65%). 

In the past, a very popular type of rechargeable battery contained cadmium (Cd), which is a very toxic metal. Cadmium is now banned by the EU for most uses. In 2006, the ofiicial Journal of the European Union in Directive 2006/66/EC, published Directive 2006/66/EC, article 4, stipulating that portable batteries or accumulators, containing more than 0.002 % of cadmium, are prohibited (European Union 2006). Although there are several types of rechargeable batteries, such as lithium-ion (Li-ion) and lithium-ion-polymer (Li-ion polymer), nickel-metal-hydride batteries (NiMH-batteries) are a very common type. 

The demand for the lanthanoid metals is expected to increase with the growing demands for pollution control catalysts in motor vehicles and rechargeable batteries. Along with lithium-ion batteries, nickel-metal hydride (NiMH) batteries find increasing applications in mobile phones, laptop computers and other portable electronic devices such as MP3 players. 

Rechargeable batteries are extensively used in household and industrial appli-catimis. Nickel-cadmium (NiCd) batteries were the only suitable batteries for portable applications for many years. Nickel metal hydride (NiMH) batteries, however, have replaced the NiCd batteries in many applications, after they were developed in 1989 and commercialized primarily in Japan in 1990 (Bernards et al., 2004). Electrochemical properties of the NiMH batteries... 

Size, weight, capacity, and power density are the primary selection considerations for batteries in externally powered prosthetic design applications. The most popular types of rechargeable batteries in use in prosthetics today are nickel-cadmium (NiCd), nickel-metal-hydride (NiMH), and lithium-ion (Li-ion). Li-ion is fast becoming the chemistry of choice because of its high capacity-to-size (weight) ratio and low self-discharge characteristic. 

Nickel-metal-hydride (NiMH) battery (13.5) Secondary (rechargeable) battery used in many small electronic devices involves the oxidation of hydrogen from a metal hydride and the reduction of nickel oxyhydroxide (NiO(OH)). Compared with nicad batteries, NiMH eliminates the use of toxic cadmium and is less prone to memory effects. 

Recycling and refining of spent rechargeable batteries (NiMH and Li-ion)... 

Recommended battery seminars are the Power Conference, Annual Battery Conference, The International Seminar on Primary and Secondary Battery Technology and Application, andthe Power Source Conference, Mobile Communications magazine frequently feature articles addressing new battery technologies. This information is commonly user-oriented and provides hints on how to get the most out of rechargeable batteries. Additional battery information can be found on the Web under NiCd, NiMH, Battery Analyzer, or Battery, in general. 

Two of the other most common rechargeable battery systems are nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) that utilize KOH electrolytes. The use of alkaline conditions means the charge discharge mechanism involves no change to the electrolyte composition and exhibits a very flat discharge profile [3]. The chemistry of NiCd provides longer cycle life, very low maintenance, and better charge retention than lead acid... 

Some of the commonly used secondary rechargeable batteries are lead acid, Li-ion, Li metal, Ni-Cd, NiMH, and Zn-air. 

The ubiquity of power electronic products such as laptops, cell phones, and digital cameras, as well as the growth in popularity of hybrid electric vehicles, drive the need for efficient, long-lasting, rechargeable batteries. The most common types include the nickel-cadmium (NiCad) battery, the nickel-metal hydride (NiMH) battery, and the lithium ion battery. 

Since portable computers have unique characteristics as a result of the portability, they have unique accessories as well. First of all, portable computers can use either of two power sources batteries or AC power. There are many different sizes and shapes of batteries, but most of them are either Nickel-Cadmium (NiCad), Lithium Ion, or Nickel Metal Hydride (NiMH). All of these perform equally well as batteries, but NiCad batteries can only be recharged a finite number of times. After a time, they develop a memory and must be recharged on a special deep charging machine. NiMH and Lithium Ion batteries don t normally develop a memory and can be recharged many times, but they re a little more expensive. 

Another alloy is lanthanum-nickel-hydride. NiMH batteries are an alkaline storage battery due to the use of potassium hydroxide (KOH) as the electrolyte. The batteries are rechargeable and form a dominant factor in the market. A highly-used... 

Rare earth elements have an essential role in permanent magnets, lamp phosphors, rechargeable NiMH batteries, catalysts and other applications (see Chap. 5). In 2010, the European Union published the report Critical Raw Materials for the EU , indicating that the rare earths had the highest supply risk of all raw materials, while their economic importance was considered medium (European Union 2010) (Fig. 7.1). 

Fig. 7.6 Rechargeable NiMH battery for a Toyota Prius. Source Wikimedia commons. Original Photograph by Hatsukari715...

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