The Lithium Polymer Battery(1) The Lithium Polymer Battery(1)
The Li -polymer differentiates itself from other battery systems in the type of electrolyte used. The original design, dating back to the 1970s, uses a dry solid polymer electrolyte only. This electrolyte resembles a plastic-like film that does not conduct electricity but allows an exchange of ions (electrically charged atoms or groups of atoms). The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte. The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry. There is no danger of flammability because no liquid or gelled electrolyte is used. With a cell thickness measuring as little as one millimeter (0.039 inches), equipment designers are left to their own imagination in terms of form, shape and size. It is possible to create designs which form part of a protective housing, are in the shape of a mat that can be rolled up, or are even embedded into a carrying case or piece of clothing. Such innovative batteries are still a few years away, especially for the commercial market. Unfortunately, the dry Li-polymer suffers from poor conductivity. Internal resistance is too high and cannot deliver the current bursts needed for modern communication devices and spinning up the hard drives of mobile computing equipment. Although heating the cell to 60 °C (140°F) and higher increases the conductivity to acceptable levels, this requirement is unsuitable in commercial applications. Research is continuing to develop a dry solid Li-polymer battery that performs at room temperature. A dry solid Li-polymer version is expected to be commercially available by 2005. It is expected to be very stable; would run 1000 full cycles and would have higher energy densities than today’s Li-ion battery. more info:www.good-battery.com
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