A team of scientists has developed a paper battery that is activated by water and has a voltage of 1.2 volts , almost the same as a typical alkaline battery, which has 1.5 volts. The materials with which the battery is made are biodegradable and sustainable, so the battery could have a significant impact on single-use electronics, that is, temporary devices used in the medical and industrial fields, where electronic waste accumulates quickly.
The battery has more advantages and is that according to the researchers, it is cheap to manufacture and can be made in different shapes and sizes according to the needs.
To give us an idea of the power of this innovative battery, a two-cell battery made with this technology was enough to power an LCD alarm clock. Of course, with it we will not be able to load a laptop. Where it will work well is on low power sensors and trackers .
“Introducing a printed paper battery developed to power single-use disposable electronics while minimizing their environmental impact,” the researchers write in the article published in Scientific Reports . “The battery is based on a metal-air electrochemical cell that uses zinc as the biodegradable metal in the anode, graphite in the cathode, paper as the separator between the electrodes, and a water-based electrolyte.”
The battery, made of paper distilled with sodium chloride salt, can measure as little as one square centimeter , and is based on printed inks: one ink contains flakes of graphite and acts as a cathode (positive end), while another, in the other side of the paper, contains zinc powder and acts as the anode (negative end). A third ink, made up of carbon black and graphite flakes, is printed on both sides, on top of the other two inks, connecting the positive and negative ends to two wires. These are fixed at one end of the paper, dipped in wax.
To activate the mechanism we will need a small amount of water , which can be two drops. The water will dissolve the salts within the paper, releasing charged ions which will then activate the battery on its way. The circuit is closed by attaching the wires to the electrical device, which means that electrons can be transferred from the negative to the positive ends.
With a stable voltage of 1.2 volts, the paper stack approaches the power of a standard 1.5 volt AA alkaline battery. The paper battery starts to produce power only about 20 seconds after the water is added, according to the team’s experiments.
“This demonstration shows that despite its limited power density compared to standard technologies, our battery is still relevant to a wide range of low-power electronics and the Internet of Things ecosystem,” the researchers write.
The performance of the stack decreases over time as the paper dries out. However, it can be topped up to a certain point with more water and it will still work. In this way, the battery can still produce 0.5 volts two hours after it is first activated.
For now, this is just a test and the scientists want to improve the efficiency of the battery for the future, so that it works for longer. The battery, yes, is not difficult to produce.
“With the growing 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 low environmental impact,” they write. the researchers in the study.
“This shift from traditional performance-oriented figures of merit creates new opportunities for unconventional materials and designs that can provide a balance between performance and environmental impact.”
Referencia: Poulin, A., Aeby, X. & Nyström, G. 2022. Water activated disposable paper battery. Scientific Reports. DOI: https://doi.org/10.1038/s41598-022-15900-5
