Every day, countless electrical devices are produced that need a battery as a source of energy. These batteries have a negative impact on our environment. But now a solution has come up that can change everything, and Empa scientists have made a mini capacitor that decomposes easily in nature. It consists of carbon, cellulose, glycerin and table salt.

Production of a unique biodegradable battery

This device for a revolution in the world of batteries works reliably. It is manufactured using a commonly available 3D printer, which is located in the Empa laboratory building. An important component is the gelatin ink that the printer dispenses to the surface. This mixture in question consists of cellulose nanofibers and cellulose nanocrystallites, plus carbon in the form of carbon black, graphite and activated carbon.

Glycerin, water and various types of alcohol are used to liquefy this mixture. A pinch of salt is also used to ensure sufficient conductivity. In order for this mixture to form a functional supercapacitor, it is necessary for the 3D printer to apply 4 layers. It is a flexible substrate, conductive layer, electrode and electrolyte. The resulting mini-capacitor can store electricity for hours and power, for example, a digital watch. Its longevity is long, it can withstand thousands of charging and discharging cycles. It is resistant to frost, pressure and shocks. It can be stored for years without compromising its functionality.

Batteries that decompose in nature

While a normal battery would not decompose in nature for decades, you can easily throw this battery into compost and it will gradually decompose.

“It sounds quite simple, but it wasn’t at all,” says Xavier Aeby of Empa’s Cellulose & Wood Materials lab. It took an extended series of tests until all the parameters were right, until all the components flowed reliably from the printer and the capacitor worked. Says Aeby: “As researchers, we don’t want to just fiddle about, we also want to understand what’s happening inside our materials.”

Aeby is collaborating with his superior Gustav Nyström, who has long been researching functional gels based on nanocellulose.

“The project of a biodegradable electricity storage system has been close to my heart for a long time,” Nyström says. “We applied for Empa internal funding with our project, Printed Paper Batteries, and were able to start our activities with this funding. Now we have achieved our first goal.”

Nyström expects that decomposable batteries could become a common part of the Internet of Things in the future and could be powered by an electromagnetic field. Such a project is very important for the whole world, a huge amount of batteries is produced every day. If a large part of all the batteries produced were biodegradable, we would certainly help the environment.

Source & credit: Empa