New polymer gel for cheaper, flexible lithium ion batteries
By Ben Coxworth
September 13, 2011
Lithium-ion batteries have certainly been a boon to electronic devices, offering much longer run times than their alkaline counterparts. There is still room for improvement, however. Existing lithium batteries can short circuit, they don't stand up to damage, and they can only be made in a limited variety of shapes. Now, scientists from the University of Leeds have developed a polymer gel that could be used to make lithium batteries with none of those shortcomings - plus, they should be cheaper.
Traditional lithium-ion batteries consist of sealed cells that each contain a porous polymer film separator and a liquid chemical electrolyte. The pores in that separator allow charged lithium ions to flow between the electrodes, while acting as a barrier that keeps those electrodes from contacting one another and shorting out.
That separator isn't needed with the new gel. In a patented high-speed extrusion/lamination process, the gel is sandwiched between an anode and a cathode. The result is a highly-conductive strip, that is nanometers thick. It is flexible, damage-tolerant, and can be cut to any size. Its fully-automated production process is said to be cost-effective and safe, as it doesn't result in any excess flammable solvents or liquid electrolytes.
The gel itself contains about 70 percent liquid electrolyte which is mixed with a polymer. The two liquids are mixed with hot water, and set into a gelatinous consistency as they cool.
The technology was developed by Ian Ward, a Research Professor of Physics at Leeds. It has been licensed to American company Polystor Energy Corporation, which is in the process of conducting trials in preparation for commercialization.
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