Cell phone batteries

Battery is the lifeblood of a mobile phone.All batteries contain one or more cells. A cell is the working chemical unit inside a battery. A cell has three main parts: a positive electrode (terminal), a negative electrode, and a liquid or solid separating them called the electrolyte.

How rechargeable batteries work?

Batteries convert stored chemical energy into electrical energy. This is achieved by causing electrons to flow whenever there is a conductive path between the cell's electrodes.  Electrons flow as a result of a chemical reaction between the cell's two electrodes that are separated by an electrolyte. When a battery is connected to an electric circuit, a chemical reaction takes place in the electrolyte causing ions to flow through it one way, with electrons flowing through the outer circuit in the other direction. This movement of electric charge makes an electric current flow through the cell and through the circuit it is connected to.

The cell becomes exhausted when the active materials inside the cell are depleted and the chemical reactions become slow. The voltage provided by a cell depends on the electrode material, their surface area and material between the electrodes (electrolyte). Current flow stops when the connection between the electrodes is removed.

Rechargeable cells operate on the same principle, except that the chemical reaction that occurs is reversed while charging. When connected to an appropriate charger, cells convert electrical energy back into potential chemical energy. The process is repeated every time the cell is discharged and recharged.

The capacity of cells is expressed in amp-hours (Ah) or milliamp-hours (mAh).


There are four basic types of rechargeable battery used in mobile phones:

•    Nickel Cadmium (NiCd) Batteries

Nickel Cadmium cell phone batteries are based on old technology.  

NiCd batteries suffer from memory effect (happens when rechargeable batteries are not fully discharged between charge cycles; as a result the battery “remembers” the shortened cycle and is thus reduced in capacity). They must be completely discharged before recharging or else damage can occur. The chemicals used in NiCd batteries are not environmentally friendly, and the disposal of cadmium-rich waste is an increasing problem.

They are the cheapest variety of phone batteries. Their affordablility helps to bring down the overall cost of mobile phones.

•    Nickel Metal Hydride (NiMH) Batteries

Nickel Metal Hydride (NiMH) batteries claim to be superior to NiCd because they don't contain cadmium. The cell phone batteries are made from non-toxic materials and are environmentally friendly. They also deliver a higher capacity in relation to their size and weight.

NiMH cell phone batteries are relatively new technology and are prone to the “memory effect", but only to a very small extent. To maximize performance, it is advised to completely discharge the battery after every 20th recharge.

•    Lithium Ion (Li-Ion) Batteries

This is the current and most popular technology for cell phone batteries. The only real drawback of Lithium Ion cell phone batteries is that they are expensive. As such, they tend to be supplied with only top-of-the-line phones. Lithium Ion batteries are slightly lighter than NiMH batteries, but they also have a longer lifetime.

A Lithium Ion battery may be damaged by extensive overcharging (continuously on a cell phone charger for more than 24 hours).

•    Lithium Polymer (Li-Poly) Batteries

Li-Poly Batteries are the newest and most advanced technology for cell phone batteries. Ultra-lightweight, they do not suffer from memory effect and will deliver up to 40% more battery capacity than a Nickel Metal Hydride (NiMH) of the same size.