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Iowa State University’s lithium-ion battery is capable of producing 2.5V and dissolves/dissipates in 30-minutes when exposed to water. (via Iowa State)

 

Normally, when it comes to lithium-ion batteries we prefer them to be robust and not easily damaged while retaining a long lasting shelf life. A team of scientists from the University of Iowa on the other hand, created almost the exact opposite of what we would consider great features with a Li-ion battery that self-destructs when exposed to water. In other words, it’s not ideally suited for use in today’s smartphones, which have a tendency to wind up in a pool of liquid more often than not.

 

On the other hand, these types of batteries would be perfect for military applications where sensitive devices would need a self-destructive capability before they wound up in enemy hands. They would most certainly benefit other applications as well, such as environmental sensors that would deteriorate when exposed to rain or even used in implantable medical devices that dissolve over a specific period of time, negating the need to be surgically removed.

 

The battery is actually part of a new field of study known as ‘transient electronics’, which are essentially electronic devices that can perform a variety of functions but decay quickly when exposed to heat, light or liquids. The team, led by assistant professor of mechanical engineering Reza Montazami designed the first transient battery that could power such devices and maintain the power, shelf life and stability needed for practical applications.

 

The team designed their battery using the same Lithium-ion chemistry found on the commercial market- carbon for the negative electrode and a silver-metal oxide for the positive electrode with a lithium-salt/organic solvent acting as the electrolyte. All of which was then wrapped in a pair of polyvinyl alcohol-based polymer layers. Don’t let the above picture fool you as the battery measures in at 6-millimeters wide, 5-millimeters long and just 1-millimeter thick.

 

When dropped in water the liquid causes the casing to swell, thereby breaking apart the electrodes and dissolving away in just 30-minutes. It does have one caveat though- it doesn’t completely disappear as the nano-particles in the electrodes don’t degrade, however they do disperse when the casing breaks apart. Add to the fact that it only produces 2.5V (enough to power a desktop calculator), it doesn’t have much practical applications at this point beyond powering a simple sensor device. The team did state however, that the battery could be made to produce more power but it would increase its size, which in-turn would take longer to dissolve. Chaining several together could also be an option for devices requiring increased power.

 

For more information on the University of Iowa’s transient battery head here (http://onlinelibrary.wiley.com/doi/10.1002/polb.24113/full)

 

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