Compact and rechargeable lithium-ion batteries power our
laptops, cell phones and electric cars, but with a significant drawback:
Occasionally, the batteries burst into flames.
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| Smart Battery - Mark Shwartz/Precourt Institute for Energy, Stanford University |
Now, Material scientists have found an amazing technique to alert users of damaged batteries before any hazard occurs, they published their research in Nature Communications.
A typical
lithium-ion cell consists of a lithium oxide as cathode and a graphite as anode,
separated by a thin, porous polymer sheet that allows ions to travel between
the electrodes. When the cell is overcharged, microscopic chains of lithium,
called “dendrites,” sprout from the anode and pierce through the polymer
separator until they touch the cathode. An electrical current passing through
the dendrites to the cathode can short-circuit the cell, which causes
overheating and, in some cases, fire.
As an attempt to stop this, a smart
separator have been built by sandwiching a 50-nanometer thin copper layer between two polymer sheets and connecting the copper layer to a
third electrode for voltage measurement. When the dendrites reach the
separator, the voltage between the anode and the copper layer drops to zero,
alerting users that they should change the damaged battery.
This detection mechanism is highly sensitive, accurate and activated well in advance of shorting and can be applied to many types of batteries for improved safety.
Source: Sciencemag, Nature Communications
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