The old saying goes that you could wait for hours to catch a bus and then two come along at once. The subject of last week’s TechTalk was how cellulose derived from trees could be used to make the electrolyte for a solid-state battery that may overcome the previous downsides to the technology (their brittleness and short lifetime). It seems there is always something can be found in nature to help our research along. This week I was reading some of the media articles on the COP 26 conference in Glasgow and found out that there was a lot more events for the public than I had previously assumed, which did make me feel a little guilty for not looking into it beforehand and taking the 40 minute train ride up to Glasgow. One of the events that I missed was the sustainability awards. The winner of the Startup for Climate award was Linköping University, where researchers were awarded the prize for two innovations - the manufacture of wood-based electrodes in rolled form, and a new type of water-based electrolyte, which both come together to be used in large-scale energy storage.
The safe, cheap and sustainable technology was developed by the Laboratory of Organic Electronics at Linköping University and the results were published in the scientific journal Advanced Energy and Sustainability Research. The technology has been patented and will be commercialised by Norrköping-based spin-off company Ligna Energy AB. Professor Xavier Crispin and his colleagues have developed the concept for large-scale energy storage with a potential power output that is high enough for the technology to maintain power balance in the electricity supply.
“Our results allow for safe, environmentally sustainable organic energy storage with high power density, 5 kW/kg, where the electrodes are manufactured from wood-based material in a printing press. We must, however, increase the energy density: our organic batteries are better than normal supercapacitors, and have about the same performance as lead-acid batteries. But lithium-ion batteries are better”, quotes Crispin.
There have been previous attempts to design a sustainable system for energy storage based on cheap organic and water-based electrolytes with carbon-based electrodes, however, they all have had problems with rapid self-discharge: making it difficult to achieve more than 24 hours
The results from Linköping team are based on two breakthroughs - a new type of water-based electrolyte, and electrodes made from lignin, which is a readily available, cheap by-product from the paper manufacturing. A polyelectrolyte was developed that consists of a highly concentrated water-based polymer, potassium polyacrylate, biopolymer lignin (positive electrode) and polyimide mixed with conductive carbon (negative electrode).
“The voltage drop, which measures the self-discharge, is less than 0.5 V in 100 hours, which is a record for energy storage with organic electrodes in water-based electrolytes”, says Crispin.
The lignin, carbon and the polyelectrolyte cost less than 1 USD/kg, are readily available, non-flammable, and the technology can be scaled up to large batteries.