Scientists invent a paper battery that works with just a drop of water

A new “just add water” disposable paper battery could power small-scale electronics such as smart tags for package tracking and medical diagnostic devices.

Because it’s made of paper and contains zinc, both of which are biodegradable, scientists say it could help reduce the environmental impact of these types of batteries.

Designed by Gustav Nyström and his colleagues at the Swiss Federal Laboratories for Materials Science and Technology, the battery is made up of at least one cell that measures one square centimeter or about 0.15 square inches. The team published their findings in the Scientific reports newspaper on July 28.

Three ink marks cover a rectangular piece of paper on which is sodium chloride, i.e. table salt, while one end of the paper is dipped in wax.

The new ‘just add water’ disposable paper battery designed by Gustav Nyström shown in an undated photograph. The battery is made of paper and contains zinc, both of which are biodegradable and could have a positive impact on the environment.
SWNS/Zenger/Matthieu Newby

On one side of the paper is the first ink marking, which contains flakes of graphite and acts as the positive end of the battery.

On the other side is another ink marking that contains zinc powder and acts as the negative end of the battery.

A third ink marking is printed on both sides and contains flakes of graphite and carbon black, which connects the positive and negative ends of the battery to two wires that are at the end of the paper dipped in the wax.

Swiss disposable paper stack
The new ‘just add water’ disposable paper battery designed by Gustav Nyström shown in an undated photograph. The battery consists of at least one cell that measures one square centimeter or about 0.15 square inches.
SWNS/Zenger/Matthieu Newby

When a few drops of water are added, the salts in the paper dissolve and charged ions are released.

These ions activate the battery by dispersing through the paper and causing the zinc at the negative end to release electrons.

Electrons are transferred from there to the positive end via the graphite and carbon black ink and wires where they become oxygen and are released into the air.

All these reactions create an electric current which is used to power the device.

Presenting their work in the journal Scientific Reports, the researchers demonstrated the capabilities of their battery by combining two cells into a single battery and using it to power a digital display alarm clock.

Two drops of water activated the battery after 20 seconds and when not powering a device, it reached a voltage of 1.2 volts.

Battery
Panasonic dry cell batteries are displayed at the Panasonic booth during CES 2018 at the Las Vegas Convention Center on January 9, 2018 in Las Vegas, Nevada. When a few drops of water are added to the disposable battery, the salts in the paper dissolve and charged ions are released.
Getty Images/David Becker

By comparison, the voltage of a standard AA battery used for TV remotes and toys is 1.5 volts.

Battery performance dropped dramatically after an hour as the paper dried out but when two more drops of water were added it maintained a stable voltage of 0.5 volts for another hour and more.

Nyström and his colleagues say the biodegradability of paper and zinc means their battery could minimize the environmental impact of low-power electronics.

The researchers say it could be further improved by reducing the amount of zinc used in the ink, which would also mean the electricity generated by the battery could be controlled more precisely.

Produced in association with SWNS.

This story was provided to Newsweek by Zenger News.

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