The Swiss Federal Laboratories for Materials Science and Technology (Empa) have created a battery that almost completely decomposes in natural conditions. At the same time, it is easy to manufacture: you can print the battery using a 3D printer, writes Semiconductor Digest.
The biodegradable battery generates electricity through a chemical reaction, just like a regular finger battery, only the materials from which the elements of the new device are made are environmentally friendly.
The battery consists of a flexible substrate, a conductive layer, an electrode and an electrolyte, which are printed in layers (in the same sequence as listed) on a conventional 3D printer. Then the finished layers are folded into a sandwich with the electrolyte in the center.
The composition was carefully selected for each layer. The substrate materials are nanofibers and cellulose nanocrystals mixed with glycerin. The components of the conductive layer are graphite, carbon black and shellac (natural resin). The electrode is made of the same materials as the substrate, but with the addition of activated carbon and graphite. And the electrolyte consists of nanocrystals of cellulose, glycerol, and a small amount of table salt to provide ionic conductivity.
“It sounds pretty simple, but it wasn’t like that at all. It took a long series of tests to establish the correct parameters for the printer to print what was needed and the battery to work, ” Xavier Eby, an employee of the Empa Pulp and Wood Materials Laboratory and one of the authors of the development, told Semiconductor Digest.
The composition of the ink for the 3D printer is selected in such a way as to ensure uniform application and solidification of the materials without losing their properties: electrical conductivity for the electrode layer, ionic conductivity for the electrolyte and strength for the battery case.
As tests have shown, the invented battery retains electricity for several hours and can even power a small electronic clock. It can withstand thousands of recharge cycles, high pressure, low temperatures, and can be stored for several years without losing these properties. But the main advantage of a biodegradable battery, the creators call environmental friendliness. Because after using it, it is enough to throw it into a compost pit, and after a couple of months, almost nothing will remain from the battery.