Li-ion Lithium Ion Battery Technology Overview

- information, tutorial about the basics of Li-ion, lithium ion battery technology giving an overview of how they work, how to use them to their best and their applications.

This overview or tutorial about battery technology is split into several pages, each addressing a particular type of aspect of battery technology:

Lithium ion, or Li-ion batteries are now being widely used for applications such as powering laptop computers, mobile phones cameras and many more devices. The high energy density that Li-ion batteries provide, enables the electronic devices they power to be recharged less frequently. Also Li-ion batteries are comparatively light when compared to other forms of rechargeable cells and batteries.

In view of their convenience, Li-ion, lithium ion batteries are widely used and there are a number of different manufacturers for these batteries. Accordingly costs have fallen from their original high levels, although Li-ion batteries are still expensive..

Lithium ion, Li-ion battery basics

The lithium ion cell is comparatively complicated to manufacture, requiring over 30 components. Basically it consists of a lithium cobalite cathode and a graphite anode. These are wound tightly together so that they can be placed into a cylinder along with a plastic insulator. The cylinder is then filled with an electrolyte and the end is capped.

Li-ion charge discharge characteristics

Unlike the NiCd and NiMH cells which exhibit very similar characteristics the Li-ion cell is quite different. The cell potential starts at around four volts, decaying to around three volts before it is said to be discharged. This has a number of advantages. Items like cell phones require a minimum operating voltage of around three volts. This can be provided by a single Li-ion cell. Having a single cell also simplifies charging.

Other characteristics of the Li-ion cell show improvements over its competitors. It has been shown to be able to withstand over 1000 charge/discharge cycles and still be able to hold 80% of its initial capacity. NiCds offer up to around 500 cycles, although this is very dependent upon the way they are used. A badly treated cell may only give 50 or 100. NiMH cells are even worse, and this is one of the main areas receiving development. They are only able to give 500 cycles at the very best before their capacity drops to 80% of the initial charge rating.

Guidelines for using Li-ion batteries

Lithium ion batteries or Li-ion batteries can be relatively expensive. It therefore pays to follow simple guidelines that can help ensure the maximum life is obtained from them.

1. Lithium-ion batteries should be charged before the battery is completely discharged.


2. Lithium-ion batteries should not be frequently fully discharged and recharged ("deep-cycled") like Ni-Cd batteries. However this may be needed occasionally to recalibrate any associated "fuel gauge" circuitry used to monitor the state of charge, control charging, etc.


3. Li-ion batteries should never be depleted to below their minimum voltage, 2.4 V to 3.0 V per cell.


4. If a Li-ion battery is not to be used for an extended period of time it should ideally be brought to a charge level of between about 40% and 60% of full charge.


5. Li-ion batteries should be kept cool. By keeping them cool, possibly in a refrigerator, the ageing process becomes slower. As a result, Li-ion batteries should not be kept in cars on sunny days as the temperatures rise significantly.


6. Li-ion batteries should not be exposed to very low temperatures - most lithium-ion battery electrolytes freeze at approximately ?40 °C. This may preclude them from some applications where equipment needs powering in extremes of temperature.


7. Li-ion batteries should be bought only when needed, because the aging process begins as soon as the battery is manufactured

Li-ion summary

Li-ion batteries and cells or li-ion batteries and cells are now in widespread use. They have taken a position of dominance in the rechargeable battery market and as a result many mobile phones, laptop computers and cameras, etc use them. Although there are many new battery developments taking place, lithium ion batteries, li-ion batteries will remain one of the main types of battery for many years to come.

Further pages from this tutorial
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