Silicon-air battery achieves 1100 hours' running time

For the first time ever, scientists have achieved more than 1100 hours’ running time — that’s almost 46 days — with a silicon-air battery. This type of battery is being heralded as a cost-effective alternative to current energy storage technology.

Unfortunately, until now they have only ever achieved short running times. Researchers at Jülich’s Institute of Energy and Climate Research (IEK) theorised that this was due to the consumption of the electrolyte. To test this, they created a pump system in which the electrolyte flued (potassium hydroxide dissolved in water) was refilled from time to time.

“If the silicon anode remains in contact with the electrolyte, the battery will continue running,” said Hermann Tempel from the IEK’s Fundamental Electrochemistry. By topping up the electrolyte, the battery was able to achieve a running time in excess of 1000 hours, until the silicon in the battery was completely used up.

“The battery can subsequently be recharged by exchanging the anode, in other words mechanically,” said Tempel.

Silicon-air batteries have a far higher energy density and are also smaller and lighter than current lithium-ion batteries. They are also environmentally friendly and insensitive to external influences. Their most important advantage, however, is the material from which they are constructed. Silicon is the second-most abundant element in the Earth’s crust after oxygen; it is cheap and its reserves are practically inexhaustible.

The scientists are now working to find a way to keep the battery running without the need to refill the electrolyte. The key to this is to stop the battery from self-discharging, as this leads to the electrolyte fluid being used up. Additives in the electrolyte could help with this, Tempel said.

“The battery is not yet perfect, but we now know what we have to work on,” he said.