Laptops For Less Blog

How Lithium-ion Batteries Work [Part II]

Lithium-ion battery packs come in all shapes and sizes but share mostly the same components. If you were to open up a battery pack you would find several components. [It is absolutely not recommended to open the battery pack, as it can lead to shortages and/or fires!] The first component to look at is the actual battery cell. These battery cells almost resemble AA batteries in most cases. Some are shaped similar to a 9-volt battery, and they are the life blood of the battery. The pack also has several components to monitor the battery.

These components include temperature sensors to make sure the batteries do not over heat. Another component is the voltage converter and regulator circuit that monitors the draw on the battery. A voltage tap monitors each cell in
relationship to the battery. A battery charge monitor is a small computer that monitors the charge as the name implies. Lastly, the battery has a shielded connector that connects to the laptop. This part is designed to
protect the battery in the event of overheating, or a complete battery drain. [The on-board computer is the reason the batteries have a five percent draw per month when sitting idle].

The battery cells are constructed of a metal casing and several internal layers. The casing holds a tightly wound spiral consisting of three layers. These three thin sheets of material are; a positive electrode, a negative electrode and a separator. The sheets are submerged in an organic solvent to act as an electrolyte, such as ether.

The separator does as the name implies, and separates the two electrodes but still allow ions to flow through from each electrode. The positive electrode is made of Lithium Cobalt Oxide [LiCoO2]. The negative electrode is simply made from carbon.

Essentially, the electrolyte allows the ions to move from one electrode to the other during charge and discharge. During charge, the electrons move from the lithium to the carbon. During discharge the opposite happens, the electrons
move back to the lithium. All of this process is contained within the metal casing and insulation of the battery cell. A Positive Temperature Coefficient is added into the battery cell to make sure the chemical reaction does not over heat. The chemical reaction occurs at a higher voltage which produces more heat.

Normal alkaline AA cell batteries produce 1.5 volts. The voltage is required to push the electrons and cause the reaction to occur. A lithium-ion reaction occurs at a much higher voltage. In order to make the lithium ions move each
cell produces 3.7 volts. The higher voltage produced is the reason that lithium-ion batters are more compact than normal alkaline batteries. The small size allows them to be used in devices such as iPods and cell phones. This is essentially how a lithium ion battery operates. Knowing how they work allows people to understand how to prolong that life. Read on in part III of “How Lithium-ion Batteries Work” on how to prolong the life of a lithium-ion battery and explore why they can explode.

LaptopsForLess.com has a huge selection of batteries in stock, at very reasonable prices [often a fraction of the cost of manufacturers’ own brand replacements]. We stock; Laptop Batteries, Power Tool Batteries, PDA Batteries, Camera/Camcorder Batteries, Cell Phone Batteries and much more. If an electronic device contains a battery, we’ll stock that battery!