If 80 percent of Germany’s electricity is to come from wind and solar by 2050, then the country must rapidly expand its energy storage capacity. That means all battery technologies must be explored.

Zinc-air batteries are nothing new. Since the 1970s, they have been used as button cells in applications such as hearing aids, due to their high energy density and long shelf life. But until now, recharging has not been possible.

Over the past six years, a team from the FH Münster University have been working on a rechargeable Zn-air storage concept that uses oxygen from the air to convert zinc into zinc oxide in a reversible process. A large demonstrator unit has now been completed on the grounds of the utilities provider Stadtwerke Steinfurt. Resembling a futuristic walk-in chiller with a glass door, it is made up of 72 individual cells and has a storage capacity of more than 7 kw hours.

"We see great potential in this technology. With our research, we want to demonstrate an environmentally friendly, more efficient and cheaper alternative to lithium-ion batteries," explains Professor Peter Glösekötter, project lead at the Department of Electrical Engineering and Computer Science in a press release. The benefit of Zn-air over Li-ion technology is its low cost and wide availability – the mineral is commonly found in Germany.

The team worked with several industrial partners to bring the technology to pilot stage including EMG Automation, 3e Batterie-Systeme and, in the latest phase, with the engineering firm Kunkel + Partner. "Our goal is to turn the demonstrator into a marketable product," emphasises Glösekötter. After learnings from the pilot have been absorbed, the next step is to establish a spin-off to bring the battery to market.

The project "Power Density Optimised Zinc-Air Storage - P-ZLS" was funded by the EFRE NRW programme and the Federal Ministry of Education and Research (BMBF) with around EUR 1.2 million.