NiMH battery

These batteries are much cheaper to make than earlier nickel battery types, and have an energy density almost double that of lead-acid. NiMH batteries can accept three times as many charge cycles as lead-acid, and work better in cold weather. NiMH batteries have proven effective in laptop computers, cellular phones, and video cameras. 

NiMH batteries can power an electric vehicle for over 100 miles, but are still several times more expensive than lead-acid. NiMH batteries from Energy Conversion Devices were installed in GM s EVj and S-10 electric pickup truck, doubling the range of each. Chrysler has also used... 

NiMH batteries, made by SAFT of France its Electric Powered Interurban Commuter (EPIC) vans, adding 30 miles to their range. 

The AB5 hydrogen storage alloy for the production of NiMH batteries has been industrialized in China and international markets. In 2005, global sales volume of the alloy was L Corresponding author... 

The sealed nickel—metal hydride battery has characteristics very similar to those of the sealed NiCd battery. The main difference is that the NiMH battery uses hydrogen, absorbed in a metal alloy, for the active negative material in place of the cadmium used in the NiCd battery. The NiMH batteries have a higher energy density and are considered more environmentally friendly than the NiCd battery. The sealed NiMH battery, however, does not have the very high rate capability of NiCd battery, and is less tolerant of overcharge. 

Ikoma et al. carried out a detailed investigation to study the self-discharge mechanism and contribution of separators.They used nonwoven fabric made of conventional polyamide (FA), FF (with surfactant), and a nonwoven fabric whose main material was sulfonated-FF (hydrophilic) as separators. When nonwoven fabric made of chemically stable sulfonated-FF is used as a separator instead of a conventional polyamide separator, the self-discharge rate of the NiMH battery was strongly depressed, to the same level as that of NiCd battery. 2 >o-242.243... 

Cheng et al. carried out the impedance study on a foam-type NiMH battery with nonwoven PP separator to determine the main causes of early cycle deterioration. Their data indicated that the decrease in the voltage characteristic of the battery was due to drying out of the separator that increases the ohmic resistance of the battery and that decay of the total discharge capacity is due to an inactive surface that increases the charge-transfer of the battery. 

Lead-acid, nickel-iron (Ni-Fe), nickel-cadmium (NiCd), and nickel-metal hydride (NiMH) batteries are the most important examples of batteries with aqueous electrolytes. In lead-acid batteries, the overall electrochemical reaction upon discharge consists of a comproportionation of Pb° and Pb4+ to Pb2+. All nickel-containing battery reactions are based on the same cathodic reduction of Ni3+ to Ni2+, but utilize different anodic reactions providing the electrons. Owing to toxicity and environmental concerns, the formerly widely used Cd°/Cd2+ couple (NiCd cells) has been almost entirely replaced by H/H+, with the hydrogen being stored in a special intermetallic compound (NiMH). 

The rare earth based metal hydrides AB5 have proven to be best suited for use in the negative electrode in NiMH batteries. The market demand for the nickel-metal hydride battery is high because of the rapid demand for portable electronics goods such as video cameras, shavers, power tools, cellular phones, lap-top computers which use high performance batteries. 

Some solid-state metal hydrides are commercially (and in some cases potentially) very important because they are a safe and efficient way to store highly flammable hydrogen gas (for example, in nickel-metal hydride (NiMH) batteries). However, from a structural and theoretical point of view many aspects of metal-hydrogen bonding are still not well understood, and it is hoped that the accurate analysis of H positions in the various interstitial sites of the previously described covalent, molecular metal hydride cluster complexes will serve as models for H atoms in binary or more complex solid state hydride systems. For example, we can speculate that the octahedral cavities are more spacious in which H atoms can rattle around , while tetrahedral sites have less space and may even have to experience some expansion to accommodate a H atom. 

Figure 4.9. Hybrid fuel cell bus, showing placement of power equipment (68 kW PEM cell, 2x75 kW motor and NiMH batteries) (MAN, 2004 used by permission.)...

Lanthanum is also used in nickel-metal hydride (NiMH) batteries found in some hybrid cars. 

Nickel is also very popular in the manufacture of batteries. Nickel-cadmium (nicad) and nickel-metal hydride (NiMH) batteries are the most popular of these batteries. They are used in a great variety of appliances and electronics, including hand-held power tools, compact disc (CD)... 

Evaluated on US FTP driving cycle, NiMH batteries for electric drivetrains... 

Include carrier distribution efficiency (93% for electricity, 86% for compressed hydrogen [52]) Taken from Ref. [52], evaluated on US FTP driving cycle, NiMH batteries for electric drive-trains... 

The main advantage of lithium-ion batteries consists in the fact that they can be charged and discharged faster than other batteries, such as Pb-acid and NiMh batteries, because of the quick reversibility of the lithium ions. Moreover, the specific energy of lithium-ion batteries is about 150 Wh/kg, this means for electric vehicles a large increase of driving range with respect to the previous types of batteries (Fig. 5.14 Table 1.8). 

As with Pb-acid and NiMH batteries, lithium-ion batteries must be controlled during their operation to prevent that overcharging conditions might occur damaging the battery. For this reason the development of battery management systems to guarantee the correct behavior in each working condition is a key issue for this type of batteries. 

Automotive Engineering on line. NiMh battery has high-volume future, http //www.sae.org/ mags/AEI/7552. Accessed 09 February 2010... 

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). 

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... 

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. 

Abuelsamid, S. December6,2006. Cobasys providing NiMH batteries for Saturn Aura hybrid. Autobloggreen.com/2006/12/05/cobasys-providing-nimh-batteries-for-Satum-Aura-hybrid/... 

---