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A lithium-ion battery which can warn of fire hazard

A lithium-ion battery which can warn of fire hazard

Stanford scientists have developed a 'smart' lithium-ion battery that gives ample warning before it overheats and bursts into flames.
The new technology is designed for conventional lithium-ion batteries now used in billions of cellphones, laptops and other electronic devices, as well as a growing number of cars and airplanes. The lithium-ion battery that alerts users of potential overheating and fire uses an ultrathin copper sensor deposited atop a conventional battery separator (White Square).
The system can detect problems that occur during the normal operation of a battery, but it does not apply to batteries damaged in a collision or other accident.
A typical lithium-ion battery consists of two tightly packed electrodes a carbon anode and a lithium metal-oxide cathode with an ultrathin polymer separator in between. The separator keeps the electrodes apart. If it's damaged, the battery could short-circuit and ignite the flammable electrolyte solution that shuttles lithium ions back and forth.
The copper layer acts like a sensor that allows you to measure the voltage difference between the anode and the separator. When the dendrites grow long enough to reach the copper coating, the voltage drops to zero. That lets you know that the dendrites have grown halfway across the battery. It's a warning that the battery should be removed before the dendrites reach the cathode and cause a short circuit. In addition to observing a drop in voltage, co-lead author Hui Wu was able to pinpoint where the dendrites had punctured the copper conductor simply by measuring the electrical resistance between the separator and the cathode.
The copper coating on the polymer separator is only 50 nanometers thick, about 500 times thinner than the separator itself. The coated separator is quite flexible and porous, like a conventional polymer separator, so it has negligible effect on the flow of lithium ions between the cathode and the anode. Adding this thin conducting layer doesn't change the battery's performance, but it can make a huge difference as far as safety.
Source:- daily science(prepared by science and technology information center)
 

 

 

15-10-2014 10:58 AM