The Empa team has been honored by TIME magazine for pioneering innovation in the Experiments category, a category of over 20 areas that celebrate outstanding inventions each year spanning artificial intelligence, apps, electronics, fitness, nutrition and more. The selection process involves evaluating originality, creativity, effectiveness, impact, and other criteria to determine the best ideas in each area.
Empa's creation stands out among this year's award winners. The innovation includes life-mapping artificial intelligence, airborne carbon-derived diamonds, and a ground-breaking telescope. Remarkably, the number of award-winning inventions has doubled this year, reflecting the creativity of the global invention community.
A simple concept with complex engineering
Gustav Nystrom and his team have developed a new battery concept using sophisticated technology. The battery has at least one square centimeter cell containing three inks printed on a paper strip. Salt, such as table salt (sodium chloride), is poured into paper, one end of which is moistened with wax. Graphite flake ink, which serves as the battery's positive terminal (cathode), is printed on one flat side of the paper. On the opposite side, zinc powder ink is applied, acting as the negative terminal (anode) of the battery.
Another paint containing graphite flakes and carbon black is applied to both sides to form current collectors. These manifolds connect the positive and negative terminals to two wires located at the waxed end.
Water initiates activation
When a small amount of water is added, the salts inside the paper dissolve, releasing charged ions that make the electrolyte conductive. These ions activate the battery by diffusing through the paper. This triggers the oxidation of the zinc in the anode ink, releasing electrons. Closing the circuit allows these electrons to travel from the zinc anode through the ink and wires to the graphite cathode. Here they interact with the oxygen of the surrounding air, generating an electric current to power external devices.
Demonstrating the efficiency of their battery when dealing with low-power electronics, Nyström's team combined two cells to boost voltage and power an LCD alarm clock. Single cell battery testing demonstrated activation within 20 seconds after adding water. In the device-free state, the battery maintained a stable voltage of 1.2V (compared to 1.5V of a standard AA alkaline battery).
The uniqueness of the battery lies in its biodegradable paper, zinc and other components, which can significantly reduce the environmental impact of disposable low-power electronics, which is a significant step towards green electronics.