How do lithium-ion batteries work?

Lithium ion batteries are those batteries that use a lithium compound in their internal structure to act as an electrochemical cell.

Lithium is a highly reactive alkali metal with just one electron in its outermost shell. So having it play an active role in batteries is essential to create a battery with high energy density.

The lithium ion batteries are of three types mainly.

Lithium Cobalt Oxide batteries:- These batteries are commonly known as ICR batteries and use a Copper/Graphite anode (negative terminal) and a Lithium Cobalt Oxide compound as a cathode (positive terminal).
These batteries can be easily manufactured to hold very high capacities and also possess good energy densities thus making them useful for laptops, mobile phones, tablets, consumer electronics and other Personal Digital Assistants. However, due to their higher internal resistance, their use has been limited to only low drain devices with their discharge rates restricted to less than 2 Amps continuous.

2) Lithium Manganate Oxide batteries:- These are also known as IMR batteries and use a Copper/Graphite anode (negative terminal) and a Lithium Manganate Oxide compound as a cathode (positive terminal).

It is easy to manufacture IMR batteries at higher current delivery capabilities, thus making them ideal for use in Electronic Cigarettes, Portable Power Tools and Electrical Vehicles. They can give upto 20 Amps continuous and have peak current abilities of upto 40 Amps even for smaller battery sizes such as 18650 size.

3) Lithium Ferrous Phosphate batteries:- These are a special type of lithium ion batteries that use a Lithium Ferrous Phosphate compound as their cathode. They are also known as IFR batteries.

The fact is that these batteries can be manufactured to have higher discharge rates as well as lower discharge rates. They are also thermally stable and have lesser chances of explosion or thermal runaway because of the stable bonds between Lithium, Iron and the Phosphate.

Unlike their lithium ion counterparts, they can undergo 2000 charge cycles on an average, while the former can undergo only 300 to 500 charge cycles on an average.

However, the nominal voltage of the IFR batteries are 3.2 Volts with a maximum voltage of 3.6 Volts, different from conventional lithium ion batteries which have a nominal voltage of 3.6 Volts and a maximum voltage of 4.2 Volts.

This makes them an ideal replacement for Lead Acid batteries when they are in a pack of 4 cells in series. However, they need Battery Management Systems to monitor them.

The lower voltage decreases their overall energy density but IFR batteries are still useful for their applications.