We are 7.9 billion people on the planet. Many of us have one or more electronic devices. While these devices have made life more efficient, the billions of batteries come with an environmental cost. But what if we could solve the issue of adverse environmental side-effects of batteries? 

Researchers at the Nanyang Technological University, Singapore (NTU Singapore) have developed biodegradable printed paper zinc batteries

The paper-thin batteries incorporate a sandwich design and are composed of electrodes that are screen-printed on both sides of a cellulose paper that has been reinforced with hydrogel. The gel fills up the naturally found gaps between fiber in cellulose. This results in a dense separator that doesn’t allow the mixing of electrodes that are basically electrode ink screen printed on the paper.  

The anode ink is made up of carbon black and zinc, whereas the cathode ink contains manganese or nickel. 

The battery is immersed in an electrolyte and then coated with a gold thin foil to improve overall conductivity. The final product is just as thick as two strands of human hair. 

Team NTU has demonstrated 4cm x 4cm square printed paper battery that can power a small electric fan for at least 45 minutes. A major concern with paper-thin batteries is whether bending, twisting, or cutting away some parts of the paper might affect the power supply; testing demonstrates that it doesn’t. 

These batteries could potentially help us solve the issue of electronic waste. They are non-toxic, biodegradable, and have no aluminium or plastic casings to protect the battery components. Once disposed of, the battery takes only one month to break down completely in the soil. 

Biodegradable printed paper zinc batteries could prove useful in flexible electronics such as foldable smartphones. They could also be used in biochemical sensors for health monitoring.