If you have a laptop, it is most likely powered by a lithium-ion (Li-ion) battery. This type of battery has applications in a wide variety of consumer electronics, including PDAs and cell phones. They enjoy great popularity for both economic and technical reasons, in particular, because of their high load/weight ratio. If you also want to buy a cylindrical lithium-ion battery you may click here.
Lithium-ion batteries have replaced nickel-cadmium (NiCd) batteries, which were first used to power laptops, and nickel-metal hydride (NiMH) batteries, which replaced NiCd laptops battery technology.
They dominate the laptop battery market today because they are much lighter than other types of laptop batteries, last longer than other technologies, and because do not suffer from the memory effect phenomenon. Ordinary lithium-ion batteries have twice the energy density of standard nickel-cadmium batteries. In addition, lithium-ion batteries have a cell voltage of 3.6 volts versus 1.2 volts per cell of nickel-cadmium batteries.
They are more sensitive to high temperatures than other battery technologies in their ability to withstand a charge. They can fail if completely discharged, and the chemicals attached to the battery cause degradation with age, in contrast to the stronger correlation between battery failure and longer battery chemical charge/discharge cycles.
Lithium-ion computer batteries also require a protection circuit built into the battery to monitor battery charge and provide safe voltage and current readings, and ensure that the battery temperature remains within a safe operating range.