The Lithium Polymer Battery(2)



In the meantime, some Li-polymers are used as standby batteries in hot climates. One manufacturer has added heating elements

that keeps the battery in the conductive temperature range at all times. Such a battery

performs well for the application intended because high ambient temperatures do not affect

the service life of this battery in the same way it does the VRLA, for example.

To make a small Li-polymer battery conductive, some gelled electrolyte has been added.

Most of the commercial Li-polymer batteries used today for mobile phones are a hybrid and

contain gelled electrolyte. The correct term for this system is ‘Lithium Ion Polymer’.

For promotional reasons, most battery

manufacturers mark the battery simply as Li-polymer. Since the hybrid lithium polymer

is the only functioning polymer battery for portable use today, we will focus on this

chemistry.

With gelled electrolyte added, what then is the difference between Li-ion and Li-ion

polymer? Although the characteristics and performance of the two systems are very similar,

the Li-ion polymer is unique in that it uses a solid electrolyte, replacing the porous

separator. The gelled electrolyte is simply added to enhance ion conductivity.

Technical difficulties and delays in volume manufacturing have deferred the introduction of

the Li-ion polymer battery. This postponement, as some critics argue, is due to ‘cashing

in’ on the Li-ion battery. Manufacturers have

invested heavily in research, development and equipment to mass-produce the Li-ion. Now

businesses and shareholders want to see a return on their investment.

In addition, the promised superiority of the Li-ion polymer has not yet been realized. No

improvements in capacity gains have been achieved — in fact, the capacity is slightly less

than that of the standard Li-ion battery. For the present, there is no cost advantage in

using the Li-ion polymer battery. The thin

profile has, however, compelled mobile phone manufacturers to use this promising technology

for their new generation handsets.

One of the advantages of the Li-ion polymer, however, is simpler packaging because the

electrodes can easily be stacked. Foil packaging, similar to that used in the food

industry, is being used. No defined norm in cell size has been established by the industry.

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