If you own a notebook, eventually you will need to replace the rechargeable battery that was supplied with the computer when it was originally purchased. This is a fact, and is not due to any defect in the battery itself but simply because the current technologies and battery chemistries result in batteries that have limited lifespans.
A laptop computer battery is evidently a rechargeable battery, which is also known as a secondary cell. The usual battery chemistry that have been used in laptop computer batteries up to date have included nickel cadmium batteries, nickel metal hydride batteries, and lithium ion batteries. Almost all laptop computers today are shipped with lithium ion batteries.
Lithium ion batteries are most commonly used in today’s laptop computers because they have very good energy to weight ratios, are not affected from the memory loss phenomenon, and because they lose their charge slowly. Lithium ion batteries have been theorized as long ago as the 70s, but have not found working application until fairly lately. Lithium ion batteries are also more friendly to the environment as they don’t contain any heavy metals as most of the earlier battery chemistries.