The New Eco Battery – Turning Trees into Batteries

 If you thought rechargeable batteries were as environmentally-friendly as it gets, think again. Sure, they reduce landfill waste to some extent as they can be recharged and reused numerous times before being thrown away (or confined to a box along with other AA batteries you’re not sure have charge or not) but they still require rare and non-renewable metals such as cobalt to be produced.

 

Traditionally, these precious metals – which also include lithium, nickel and manganese – have been used to make the battery cathode, which is the part where current flows out. Now however, two European researchers have discovered an altogether more natural alternative that may just revolutionise the industry.

 

Image via Dearoot

 

Grzegorz Milczarek of the Poznam University of Technology in Poland teamed up with Olle Inganäs of the Linköping University in Sweden to work on proving a theory that lignin, a natural substance present in all plants, could be made to hold charge.

 

Lignin makes up between 20% and 30% of a plant’s structure and is a natural polymer (a long chain of molecules). If reading this is making you worried that yet more of our rainforests are going to be destroyed to supply the 40,000 tonnes of batteries the UK buys every year, let alone the rest of the world, then don’t worry as lignin is also a natural by-product of paper production.

 

Image via Scale Speeder

 

To turn trees into paper, they’re first cooked at a high temperature to break down the cell structure and allow it to be turned to pulp. This cooking leaves behind ‘brown liquor’, a substance rich in lignin that is normally thrown away as a waste product. However, by mixing the lignin from this otherwise useless liquid with polypyrrole, another polymer, a working battery cathode can be formed, absolutely metal free!

 

Don’t expect to see ‘tree batteries’ on the shelves of your local supermarket any time soon though – these prototype lignin-based batteries slowly lose their stored charge when not being used, so more research and development is needed to improve them and get them up to consumer standards. When they’re ready to go on sale though, expect battery prices to drop – they’ll be made from a cheap waste product after all!