Swiss scientists have created a battery of salt and paper.

Engineers have created a biodegradable battery to power small or disposable electronics such as alarm clocks, sensors, smart tags and medical diagnostic devices. The battery consists of salt-soaked paper and a wax coating with wire attached on both sides. The energy is stored in the battery until water gets on it. To activate, you need two drops of liquid and 20 seconds. Water dissolves salt and releases charged ions. They dissipate in the electrolyte, start the oxidation of the zinc in the anode, and provoke a reaction that produces energy. Without connection to electronics, the battery reaches a voltage of 1.2 volts. Productivity drops within an hour in parallel with the drying of the paper. Now scientists are working to remove this limitation.