NiCd batteries are the original type of rechargeable battery used in consumer electronics. They use nickel hydroxide and cadmium electrodes with potassium hydroxide as the electrolyte. They have been largely superseded by Ni-MH batteries.
Ni-MH batteries are used in consumer electronics and electric cars. They offer twice the energy density of NiCd rechargeable batteries and are less environmentally damaging as they don’t contain heavy metals such as cadmium. They also differ by using a metal alloy negative electrode capable of storing a large amount of electrons. The metal-hydride is produced as the charging product.
Both types of battery have a long cycle life and a long shelf life when looked after properly, Depending on their application, these types of rechargeable batteries should last between 500 and 800 charge cycles or about three years. So the more you recharge, the shorter the batteries life span.
The main cause of capacity loss is that rechargeable batteries are usually battery packs containing more than one cell, and as they’re recharged over time these cells tend to get out of balance as one cell gets slightly more charge than another.
And so the whole battery pack capacity is limited by the one that charges first and the one that discharges first. Lithium-ion batteries are made from layered sheets of aluminium foil coated with cobalt oxide acting as the cathode, with the anode being a carbon mineral coated copper sheet. The electrodes are separated by a plastic separator and immersed in a lithium electrolyte medium.
Lithium-ion batteries produce even higher energy levels than Ni-MH batteries, don’t contain toxic materials such as cadmium or mercury, and are about 35 per cent lighter than the other types of batteries.
While Polymer Lithium ion Battery will remain as the principle power source for portable electronic items such as laptop computers, they’re likely to be replaced in electric cars by lithium-oxygen batteries in the future. And that means you’ll only really have lithium in the negative half-cell, while the positive half-cell will run off oxygen from the surrounding atmosphere.