The relatively new field of “transient electronics” is all about making electronic devices that can self-destruct.
Now scientists have developed a self-destructing, lithium-ion battery capable of delivering 2.5 volts and dissolving or dissipating in 30 minutes when dropped in water. The battery can power a desktop calculator for about 15 minutes.
When you drop it in water, the polymer casing swells, breaks apart the electrodes, and dissolves away.
“Unlike conventional electronics that are designed to last for extensive periods of time, 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,” the scientists write in their paper in the Journal of Polymer Science, Part B: Polymer Physics.
And what about a transient device that depends on a standard battery?
“Any device without a transient power source isn’t really transient,” says Reza Montazami, an Iowa State University assistant professor of mechanical engineering and an associate of the US Department of Energy’s Ames Laboratory, who has been working on transient technology for years.
“This is a battery with all the working components. It’s much more complex than our previous work with transient electronics.”
Montazami’s previous, proof-of-concept project involved electronics printed on a single layer of a degradable polymer composite. The transient battery is made up of eight layers, including an anode, a cathode, and the electrolyte separator, all wrapped up in two layers of a polyvinyl alcohol-based polymer.
The battery itself is tiny—about 1 millimeter thick, 5 millimeters long, and 6 millimeters wide. Montazami says the battery components, structure, and electrochemical reactions are all very close to commercially developed battery technology.
But, when you drop it in water, the polymer casing swells, breaks apart the electrodes, and dissolves away. Montazami is quick to say the battery doesn’t completely disappear. The battery contains nanoparticles that don’t degrade, but they do disperse as the battery’s casing breaks the electrodes apart.
He calls that “physical-chemical hybrid transiency.”
And what about applications that require a longer-lasting charge? Larger batteries with higher capacities could provide more power, but they also take longer to self-destruct, according to the scientists’ paper. The paper suggests applications requiring higher power levels could be connected to several smaller batteries.
Source: Iowa State University