Paper Battery Could Power Disposable Electronics

Energy is the single most important resource in our society, and its collection and storage dictates almost every aspect of our lives. On small consequence of that concept is how we design and use electronics. While planned obsolescence is a common result of capitalist economic strategy, true disposable electronic devices are rare. A major reason for that is battery-based energy storage, which is both expensive and environmentally impactful. To solve both problems and make disposable electronic devices viable, researchers created a new paper battery.

The general public uses many alkaline batteries, like AAs and coin cells, as if they are disposable, because they are affordable and are not rechargeable. There isn't much to do with them after they go flat except toss them out or recycle them. But those batteries have a significant environmental impact, even when recycled. These batteries may be disposable from an economic standpoint, but that classification is irresponsible from an environmental standpoint. This new paper battery cell, on the other hand, would have little environmental impact after disposal.

This battery follows standard chemical battery principles, but in a new package and with relatively ecofriendly materials. It consists of a square centimeter strip of paper infused with sodium chloride salt. The cathode is printed ink containing graphite flakes. The anode is another ink with zinc powder. Both sides of the paper get an additional coat of graphite flakes and carbon black, with wax acting as an insulative. When water droplets saturate the paper, the sodium chloride salt dissolves and creates a charged ion flow (electricity).

In testing, two of these paper cells in series produced 1.2V. That was enough to power a basic alarm clock. The battery lasted for an hour before the paper dried. Rewetting the paper only produced 0.5V for another hour.

That isn't a huge amount of power, but it is more than enough for many low-power components. This paper battery could, for instance, power a simple wearablemedical sensor for enough time to gather some data and transmit that data to a nearby receiver. And because the battery doesn't activate until wetted, it is perfect for disposable devices that require long term storage.