About Lithium-ion Batteries

Lithium-ion batteries are popular because they have a number of important advantages over competing technologies:
They're generally much lighter than other types of rechargeable batteries of the same size. The electrodes of a lithium-ion battery are made of lightweight lithium and carbon. Lithium is also a highly reactive element, meaning that a lot of energy can be stored in its atomic bonds. This translates into a very high energy density for lithium-ion batteries.
They have no memory effect, which means that you do not have to completely discharge them before recharging.
Lithium-ion batteries can handle hundreds of charge/discharge cycles. (depends of the usage, i.e. 500 times for cellphone batteries)
That is not to say that lithium-ion batteries are flawless. They have a few disadvantages as well:
1.They are extremely sensitive to high temperatures. Heat causes lithium-ion battery packs to degrade much faster than they normally would.
2.If you completely discharge a lithium-ion battery, it is ruined. A lithium-ion battery pack must have an on-board computer to manage the battery. This makes them even more expensive than they already are.
3.There is a small chance that, if a lithium-ion battery pack fails, it will burst into flame.
The lithium-ion cells can be either cylindrical batteries that look almost identical to AA cells, or they can be prismatic, which means they are square or rectangular The computer, which comprises:
A voltage converter and regulator circuit to maintain safe levels of voltage and current
A shielded notebook connector that lets power and information flow in and out of the battery pack
A battery charge state monitor, which is a small computer that handles the whole charging process to make sure the batteries charge as quickly and fully as possible.
Lithium-ion battery packs are expensive, so if you want to make yours to last longer, here are some things to keep in mind:
Lithium ion chemistry prefers partial discharge to deep discharge, so it's best to avoid taking the battery all the way down to zero. Since lithium-ion chemistry does not have a "memory", you do not harm the battery pack with a partial discharge. If the voltage of a lithium-ion cell drops below a certain level, it's ruined.
Lithium-ion batteries age. They only last two to three years, even if they are sitting on a shelf unused. So do not "avoid using" the battery with the thought that the battery pack will last five years. It won't. Also, if you are buying a new battery pack, you want to make sure it really is new. If it has been sitting on a shelf in the store for a year, it won't last very long. Manufacturing dates are important.