Metal hydride-nickel cell

Development of these batteries took place at around the same time frame as lithium ion technologies in the 1980s. The NiMH type battery was used in the General Motors EV1, as well as other plug-in vehicles. The Toyota RAV4 EV, Honda EV Plus, Ford Ranger EV, and Honda Insight all use NiMH batteries. The reactions for nickel-metal hydrides are 

In the anode reaction, charge takes place from left to right and discharge occurs in the opposite direction. The metal is an intermetallic AB5-type compound. Some variation occurs in that a rare-earth mixture (typically cerium or lanthanum) is compounded with nickel, manganese, cobalt, or aluminum (for the B portion). Titanium and vanadium can also be used in AB2 intermetallic compounds with nickel, zirconium cobalt, or chromium (as the B portion), but they are rarely used due to performance issues. 

Recent changes to NiMH batteries have improved their historically weak internal leakage issues. The internal leakage (self-discharge) rate stabilizes around 0.5-1% per day at room temperature [23], The low self-discharge batteries for small applications claim to retain up to 85% of their capacity after a year when stored at room temperature. However, for auto applications, discharge rates along these lines are not yet known. 

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Newton s second law, L0 nickel, 49, 665 nickel arsenide structure, 201 nickel surface, 189 nickel tetracarbonyl, 665 nickel-metal hydride cell, 520 NiMH cell, 520 nitrate ion, 69, 99 nitration, 745 nitric acid, 629 nitric oxide, 73, 629 oxidation, 549 nitride, 627 nitriding, 208 nitrite ion, 102 nitrogen, 120, 624 bonding in, 108 configuration, 35 photoelectron spectrum, 120... 

Other types Variable Variable Primary and secondary Nickel-metal hydride cells, sodium-sulfur batteries,... 

Nickel hydroxides, 17 111 Nickel—iron alloys, 17 101 Nickel—iron—aluminum catalyst, 17 121 Nickel—iron cells, 3 491—493 Nickel—iron—chromium alloy 825 in galvanic series, 7 805t Nickel—iron—chromium alloys, 17 102—103 Nickel—iron plating, 9 821 Nickel itch, 12 691, 701 Nickel—matrix composites, 17 104 Nickel metal, forms of, 17 95—99 Nickel metal hydride cells, 3 431, 471, 509-512... 

The manufacture of secondary batteries based on aqueous electrolytes forms a major part of the world electrochemical industry. Of this sector, the lead-acid system (and in particular SLI power sources), as described in the last chapter, is by far the most important component, but secondary alkaline cells form a significant and distinct commercial market. They are more expensive, but are particularly suited for consumer products which have relatively low capacity requirements. They are also used where good low temperature characteristics, robustness and low maintenance are important, such as in aircraft applications. Until recently the secondary alkaline industry has been dominated by the cadmium-nickel oxide ( nickel-cadmium ) cell, but two new systems are making major inroads, and may eventually displace the cadmium-nickel oxide cell - at least in the sealed cell market. These are the so-called nickel-metal hydride cell and the rechargeable zinc-manganese dioxide cell. There are also a group of important but more specialized alkaline cell systems which are in use or are under further development for traction, submarine and other applications. 

The sealed nickel-metal hydride cell (more consistently metal hydride-nickel oxide cell) has a similar chemistry to the longer-established hydro-gen-nickel oxide cell considered in Chapter 9. In most respects (including OCV and performance characteristics), it is very similar to the sealed nickel-cadmium cell, but with hydrogen absorbed in a metal alloy as the active negative material in place of cadmium. The replacement of cadmium not only increases the energy density, but also produces a more environmentally friendly power source with less severe disposal problems. The nickel-metal hydride cell, however, has lower rate capability, poorer charge retention and is less tolerant of overcharge than the nickel-cadmium cell. 

In 1990, Sanyo and Matsushita initiated large-scale commercialization of small sealed nickel-metal hydride batteries. They are now joined by Dur-acell, Toshiba and Varta in a consortium which is known as the 3C alliance (camcorders, cellular telephones and computers). Several plants have been commissioned which are each producing 100-200 million cells per annum. It is forecast that nickel-metal hydride may overtake nickel-cadmium before the end of the century. In addition to the 3Cs nickel-metal hydride cells are used for a wide variety of cordless consumer products, communications equipment and other high rate long cycle life applications. 

The self-discharge rate of RAM cells is approximately 0.01% per day, which gives them a clear superiority over nickel-cadmium and nickel-metal hydride cells (Fig. 6.19). 

Fig. 6.19 Comparison of charge retention on storage of a RENEWAL AA RAM cell with typical nickel-cadmium and nickel-metal hydride cells. (By permission of Rayovac.)...

In standard electrochemical notation, the above cell would be referred to as MH/M/aqueous KOH/Ni(OH)2/NiOOH. However, the current denomination is Ni/MH (nickel/metal hydride cell). 

Nickel-cadmium cell Ni-Cd cell Nickel-iron rechargeable cell -> Edison cell Nickel-metal hydride cell - Ni-MFlcell Nicotinamide adenine dinucleotide - NADH Nigraniline - poly aniline... 

Figure 8. Discharge curves at C/5 of same-size nickel-cadmium and nickel-metal hydride cells at 20 °C (by permission of National/Panasonic).

Special accumulators for hybrid (electric) vehicles have been developed on the basis of nickel-metal hydride cells, i.e., cars powered by electric engines in combination with other energy converters (mostly combustion engines). 

Nickei-metal-hydride batteries have become popular as rechargeable cells. The design is quite similar to the Ni-Cd cell, but nickel-metal-hydride cells are less prone to memory effects during the life of the battery. Such advances in battery technology are driven by rising demand for portable electronic devices like digital cameras. 

Nickel metal hydride cell containing a nickel hydroxide positive and a hydrogen-absorbing metal alloy negative electrode. 

Fig. 13.2 Cell balance in sealed nickel metal hydride cells...

Iwakura C, Eurukawa N, Ohishi T, Sakamoto K, Nohara S, Inoue H (2001) Nickel/metal hydride cells using an alkaline polymer gel electrolyte based on potassium salt of crosslinked poly(acrylic acid). Electrochemistry 69 659... 

In the mid-1990s several development teams (e.g. Varta) tried to improve the nickel/metal hydride system to make it applicable for electric road vehicles. Figure 4.12 shows a battery module with nickel/metal hydride cells the given... 

Technical specifications Nickel-metal-hydride-cells... 

Figure 4.12 Battery module with nickel/metal hydride cells and performance data.

But the problem can be solved, as has been shown by the development groups of rechargeable lithium-ion batteries. Nickel/metal hydride cells (having 50% more capacity and no cadmium content) had just started to penetrate the market to the debit of nickel/cadmium cells, and are being pushed away now by rechargeable lithium-ion batteries. Main applications are cellular phones, mobile phones, and video cameras. It cannot yet be foreseen whether nickel/cadmium will disappear from the market, because they cannot be substituted for in the use in tools. Never in the past has a new battery system eliminated an established system totally. 

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