August 10, 2016
Team creates self-destructing battery
Engineers from Iowa State University have taken one giant step forward in the development of self-destructing technology that could help keep military secrets out of the hands of the enemy, or eliminate the need to surgically remove temporary medical devices from patients.
Also known as transient devices, such technology could also be used in environmental monitors that could simply dissolve when exposed to rain, and now ISU mechanical engineering professor Reza Montazami and his colleagues have developed a battery suitable for use in such devices.According to Engadget and BBC News, his team’s battery is capable of delivering enough power to operate a desktop calculator for 15 minutes – and is encased in a degradable polymer composite that swells and dissolves 30 minutes after being exposed to water. Montazami is hailing the breakthrough as the first practical transient battery ever created.
The battery, which is detailed in research published recently in the Journal of Polymer Science, Part B: Polymer Physics, is 5 mm long, 1 mm thick and 6 mm wide. It is similar to traditional batteries in terms of structure and electrochemical reactions. However, because it is made from lithium-ion, it currently cannot be used in devices designed to be implanted in humans – a flaw that researchers are hoping to ultimately correct in future versions of the transient battery.
Montazami and his co-authors noted that their work is at the proof-of-concept stage, and that a battery capable of powering more sophisticated electronic equipment is still a long ways off, as they need to determine how to create larger, higher capacity versions of batteries with complex structures and multiple layers while also attempting to reduce the amount of time it would need to self-destruct. An array of multiple smaller batteries may be the key.
So how does this self-destructing battery work, anyway?
According to BBC News, the dissolving battery contains an anode, a cathode, and an electrolyte separator sandwiched within two layers of polyvinyl alcohol-based polymer. When it is exposed to water, its polymer casing starts to swell, breaking apart the electrodes and causing it to dissolve – but not completely, as the battery contains nanoparticles that do not degrade.
“Unlike conventional electronics that are designed to last for extensive periods of time,” the ISU mechanical engineering professor and his co-authors explained, “a key and unique attribute of transient electronics is to operate over a typically short and well-defined period, and undergo fast and, ideally, complete self-deconstruction and vanish when transiency is triggered.”
While developing the new battery, Montazami said that his team faced three major challenges. First, they wanted to develop a battery that could produce voltages close to the same level as a commercial battery, as many devices will not function is voltage output is low or unsteady. The next challenge, he explained in a statement, was to simulate the complex, multilayered structure of regular batteries, and the final one was to actually fabricate the power sources, which he said took several attempts due to the high degree of difficulty.
The result is a unit that self-destructs 1,000 times faster than previous attempts at such a battery, according to IEEE Spectrum, while delivering twice the voltage of prior transient power sources. “This is a battery with all the working components,” Montazami said in a statement, adding that it is “much more complex than our previous work with transient electronics.”
Image credit: Ashley Christopherson