EMPA scientists developed a disposable paper battery with the goal of reducing the environmental impact of single-use electronics for applications such as point-of-care diagnostics, smart packaging, and environmental sensing.

To create the battery, the scientists used zinc as a biodegradable metallic anode, graphite as a non-toxic cathodic material, and paper as a biodegradable substrate.

The battery remains inactive until water is supplied and absorbed by the paper substrate, taking advantage of its natural absorption behavior. Once activated, a single cell provides an open circuit potential of 1.2 V and a peak power density of 150 µW/cm2 at 0.5 mA.

The researchers created a two-cell battery in the experiment to prove their theories, and the result produced energy to power an alarm clock and its liquid crystal display.

With increasing awareness of the e-waste problem and the emergence of single-use electronics for applications such as environmental sensing and food monitoring, there is a growing need for batteries with a low environmental impact. This shift from the traditional performance-oriented figure of merits creates new opportunities for unconventional materials and designs that can provide a balance between performance and environmental impact.

Researchers at Swiss Federal Laboratories for Materials Science and Technology (EMPA) Alexandre Poulin, Xavier Aeby & Gustav Nyström

Using a piece of paper, on one side they printed a circuit with graphite ink (cathode) and on the other side they printed it with zinc powder (anode) and for electrolysis the sheet of paper was soaked with salt. To activate the battery, a drop of water is enough to start the chemical reaction that will produce energy.

How the paper battery works

“Once activated, a single cell provides an open circuit potential of 1.2 V and a peak power density of 150 µW/cm2 at 0.5 mA.”

said the researchers

The biodegradable and recyclable characteristic of the products used to manufacture the battery makes its use viable in real-time package tracking.

Both paper and zinc are biodegradable and can be recycled under the right conditions. This makes this low-power battery very useful in specific applications such as real-time packet tracking, point-of-care diagnostics, and environmental sensing.

Source: Scientific Reports.