I'm guessing that most photophiles here are interested in battery technology, so here's a ripped factsheet from Popular Science magazine about the different types of batteries we have.
Alkaline Disposable
They still exist because of convenience, not chemistry: You can buy them - for a pittance - from NY to Nepal. Perfect for occasional use devices, such as smoke detectors and TV removes, because oftheir long shelf life.
Nickel-Cadmium
Good for 1000 discharge cycles. They're toxic and suffer 'memory effect', when damaged crystals form if the cell isn't fully discharged. NiCds are rare except in power tools; their high discharge rates suit big-current draws.
Nickel Metal Hydride
Higher energy density than NiCds but only lasts up to 500 discharge cycles. Must be fully discharged monthly to preserve strength. Leading chemistry for rechargeable AAs and other standard cells. Relatively non-toxic.
Lithium Ion
Unbeatable for energy density. Up to 1000 discharge cycles without memory effects, so don't require discharging. Currently the leading chemistry for laptops, camcorders, cellphones and portable gadgets.
Lithium Ion Polymer
Variation on Li-Ion chemistry introduced in 1999. Solid, polymer innards of cell allow designers to mold battery into odd shapes so that they can squeeze it around components, maximising capacity.
Courtesy of Popular Science October 2004
Alkaline Disposable
They still exist because of convenience, not chemistry: You can buy them - for a pittance - from NY to Nepal. Perfect for occasional use devices, such as smoke detectors and TV removes, because oftheir long shelf life.
Nickel-Cadmium
Good for 1000 discharge cycles. They're toxic and suffer 'memory effect', when damaged crystals form if the cell isn't fully discharged. NiCds are rare except in power tools; their high discharge rates suit big-current draws.
Nickel Metal Hydride
Higher energy density than NiCds but only lasts up to 500 discharge cycles. Must be fully discharged monthly to preserve strength. Leading chemistry for rechargeable AAs and other standard cells. Relatively non-toxic.
Lithium Ion
Unbeatable for energy density. Up to 1000 discharge cycles without memory effects, so don't require discharging. Currently the leading chemistry for laptops, camcorders, cellphones and portable gadgets.
Lithium Ion Polymer
Variation on Li-Ion chemistry introduced in 1999. Solid, polymer innards of cell allow designers to mold battery into odd shapes so that they can squeeze it around components, maximising capacity.
Courtesy of Popular Science October 2004