Usually we want batteries that last as long as possible, and try to avoid destroying them. But that's the whole point with a new version developed in the lab at Iowa State University.

About a half an hour after the tiny lithium-ion battery got dropped into water, there was hardly any trace it ever existed.

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Led by assistant professor of mechanical engineering Reza Montazami, the Iowa State team created a complex battery that has an anode, cathode, and electrolyte separator plus several other layers wrapped up in a dissolvable polyvinyl alcohol-based polymer. The battery is only about 5 millimeters long, 6 millimeters wide, and 1 millimeter thick yet it's strong enough to deliver 2.5 volts. That's enough to power a desktop calculator for roughly 15 minutes, according to the university.

When the battery comes into contact with water, at first it behaves kind of like those Magic Grow toy animal sponges in capsules. The polymer casing swells up, breaks the electrodes apart, and everything dissolves within 30 minutes. Well, mostly. The team points out that some nanoparticles don't degrade although they do disperse.

This battery is designed for transient electronics, a relatively new field where the whole goal is to operate for a set amount of time and then completely self-destruct, the team explained in their recent article in the Journal of Polymer Science, Part B: Polymer Physics (abstract). It's all very "Mission Impossible."

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Why the heck would anyone want self-destructing power like this? Turns out the potential applications make sense. The team suggests that such a battery could go into a medical device, avoiding the need for a painful removal -- somewhat similar to absorbable sutures.

Or they could be put in military electronics that disappear quickly to prevent secret messages from getting into an enemy's hands. I kind of thought we already had tech like that, but maybe I'm just thinking of those Jason Bourne movies. There's a franchise that knows about self-destruction.

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