LITHIUM
Here in the states we constantly hear about Lithium.  It's lighter, stronger, more powerful, no memory and smaller.  The voltages with Li-on range in multiples of 3.7. Thus you will see, 3.7 -7.4 - 11.2.  Really futuristic techno-poop terminology abounds but there is a dark side and Darth Vader is well represented here. 

Here in the states we are in the 6v-12v theology (cars are twelve, most emergency lights are six) which has existed for decades and was based on 2 volts per cell as used in Sealed Lead Acid.  Sort of the standard of the industry.

This will change as Lithium gets more prolific.  That's as long as Lithium doesn't continue to blowup plants, pickup trucks and DELL, APPLE Toshiba, and Matsushita aka Panasonic, and IBM laptop computers can handle the economic loses.  There are several types of Lithium and we could write a book about the variants.  (So off to the Wikipedia on-line encyclopedia, it's a long item. For me it saves typing).

NEW FEDERAL AIRLINE REGULATIONS AS TO LITHIUM SPARE BATTERIES.

FROM WIKIPEDIA:
The term "lithium battery" refers to a family of different chemistries, comprising many types of cathodes and electrolytes. One type of lithium cell having a large energy density is the lithium-thionyl chloride cell. In this cell, a liquid mixture of thionyl chloride and lithium tetrachloroaluminate acts as the cathode and electrolyte respectively. A porous carbon material serves as a anode current collector which receives electrons from the external circuit. However, lithium-thionyl chloride batteries are generally not sold to the consumer market, and find more use in commercial/industrial applications, or are installed into devices where no consumer replacement is performed.

Lithium-thionyl chloride batteries are well suited to extremely low-current applications where long life is necessary, e.g. wireless alarm systems.
The most common type of lithium cells used in consumer applications uses metallic lithium as anode and manganese dioxide as cathode, with a salt of lithium dissolved in an organic solvent

• The Lithium batteries constructed of Lithium -Ion carry warnings about placing in fire.   Li-on can ignite if exposed to air.  In 1995, an entire SONY plant blew up in Japan so problems with Li-On are not new to SONY.  Toshiba was also involved.  It is reported this latest foo-pah will cost about 430 million dollars which has since doubled. 
   

• ADD throwing on the ground to fire cautions.  IF the small controller internally should break the battery will short and may explode.  People walk in our local battery store and pitch the dead ones on the counter. Boom. 
   

• A gentleman in South Korea made the papers when his cell phone went off in his ear.  He no longer resides on earth.
   

• In the 80's Lithium EPIRBS (ELT's in those days) were recalled from aircraft as they leaked and corroded control cables!) Buying cheap Lithium batteries are a stupid thing to do. 
   

• Lithium batteries find application in many long-life, critical devices, such as artificial pacemakers and other implantable electronic medical devices. These devices use specialized lithium-iodide batteries designed to last 15 or more years.
   

• Lithium batteries can be used in place of ordinary alkaline cells in many devices, such as clocks and cameras. Although they are more costly, lithium cells will provide much longer life, thereby minimizing battery replacement. However, attention must be given to the higher voltage developed by the lithium cells before using them as a drop-in replacement in devices that normally use ordinary cells.
   

• Small lithium batteries are very commonly used in small, portable electronic devices, such as PDAs, watches, thermometers, and calculators, as backup batteries in computers and communication equipment, and in remote car locks. They are available in many shapes and sizes, with a common variety being the 3 volt "coin" type manganese variety, typically 20 mm in diameter and 1.6–4 mm thick. The heavy electrical demands of many of these devices make lithium batteries a particularly attractive option. In particular, lithium batteries can easily support the brief, heavy current demands of devices such as digital cameras, and they maintain a higher voltage for a longer period than alkaline cells.
   

• Lithium batteries can provide extremely high currents and can discharge very rapidly when short-circuited. Although this is useful in applications where high currents are required, a too-rapid discharge of a lithium battery can result in overheating of the battery, rupture, and even explosion. Lithium-thionyl chloride batteries are particularly capable of this type of discharge. Consumer batteries usually incorporate over-current or thermal protection or vents in order to prevent explosion.
   

• Because of the above risks, shipping and carriage of lithium batteries is restricted in some situations, particularly transport of lithium batteries by air. Read the new regulations mandatory January 1, 2008 at the top of the page.
   
• The computer industry's drive to increase battery capacity can test the limits of sensitive components such as the membrane separator, a polyethylene or polypropylene film that is only 20-25 µm thick. The energy density of lithium-ion batteries has more than doubled since they were introduced in 1991. When the battery has more and more material, the separator can undergo stress.  In French, this translates as "Mon ami, sacre bleu, Oui de poop-e-doo". In English, "Oh Shit".
   
• Unused lithium batteries provide a convenient source of lithium metal for use as a reducing agent in illegal methamphetamine labs. Some jurisdictions have passed laws to restrict lithium battery sales or asked businesses to make voluntary restrictions in an attempt to help curb the creation of illegal meth labs.  On the good side, hopefully if there are explosions, a meth lab is a real good place for it to happen.
  
  For example a newspaper article from January 2004 reports that Wal-Mart stores limit the sale of disposable lithium batteries to three packages in Missouri and four packages in other states. However, the heavy demand for lithium batteries for use in modern, current-hungry devices such as digital cameras conflicts with such restrictions.