what's mean battery pack -The Prismatic



Cell?The prismatic cell was developed in response to consumer demand for thinner pack

sizes. Introduced in the early 1990’s, the prismatic cell makes almost maximum use of

space when stacking. Narrow and elegant battery

styles are possible that suit today’s slim-style geometry. Prismatic cells are used

predominantly for mobile

phone applications. Figure 3-3 shows the prismatic cell.

Prismatic cells are most common in the lithium battery family. The Li-ion polymer is exclusively prismatic. No

universally accepted cell size exists for Li-ion polymer batteries. One leading

manufacturer may bring out one or more sizes that fit a certain portable device, such as a

mobile phone. While

these cells are produced at high volume, other cell manufacturers follow suit and offer an

identical cell at a competitive price. Prismatic cells that have gained acceptance are the

340648 and the 340848. Measured in millimeters, '34' denotes the width, '06' or '08' the

thickness and '48' the length of the cell.

Some prismatic cells are similar in size but are off by just a small fraction. Such is the

case with the Panasonic cell that measures 34 mm by 50 mm and is 6.5 mm thick. If a few

cubic millimeters can be added for a given application, the manufacturer will do so for the

sake of higher capacities.

The disadvantage of the prismatic cell is slightly lower energy densities compared to the

cylindrical equivalent. In addition, the prismatic cell is more expensive to manufacture

and does not provide the same mechanical stability enjoyed by the cylindrical cell. To

prevent bulging when pressure builds up, heavier gauge metal is used for the container. The

manufacturer allows some degree of bulging when designing the battery pack.

The prismatic cell is offered in limited sizes and chemistries and runs from about 400mAh

to 2000mAh and higher. Because of the very large quantities required for mobile phones, special

prismatic cells are built to fit certain models. Most prismatic cells do not have a venting

system. In case of pressure build-up, the cell starts to bulge. When correctly used and

properly charged, no swelling should occur.

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