Scientists at Germany’s Federal Institute for Materials Research and Testing (BAM) are developing a next-generation battery approach using a liquid alkali metal anode, aiming to enhance the performance and practicality of solid-state batteries for everyday applications.
The initiative, part of the NASICON project, addresses a key limitation of current lithium-ion batteries: their graphite-based anodes, which have limited ion storage capacity. By switching to alkali metals like pure lithium or sodium, which offer greater energy density and sustainability, researchers hope to improve both battery efficiency and environmental impact. However, these materials require a solid electrolyte for safe operation—posing challenges due to contact loss and cavity formation between solid components.
In a breakthrough study, the team demonstrated that a liquid alkali metal anode can be “a hundred times more efficient than conventional graphite anodes,” said Gustav Graeber, battery materials expert at Humboldt University Berlin and guest researcher at BAM. The current hurdle is that such technology only functions at 250°C, prompting the team to experiment with potassium additives to lower the melting point for room-temperature operation.
The researchers are focusing on NASICON-type solid electrolytes, known for high ionic conductivity and chemical stability with potassium—especially when combined with hafnium. But due to hafnium’s scarcity and cost, the team is investigating more sustainable alternatives with similar effectiveness. Promising additives are already undergoing tests in sodium-based solid-state batteries.
“Our research project is a decisive step towards high-performance batteries that are more sustainable, cheaper and more efficient,” Graeber said. “Sodium solid-state batteries could drastically reduce charging times and significantly improve the performance of mobile and stationary energy storage systems – an important contribution to decarbonisation.”
The effort is part of a broader collaboration. BAM, Humboldt University, and the Helmholtz Centre Berlin have jointly launched the Berlin Battery Lab, a new platform designed to consolidate expertise across the three institutions and provide open access to industry partners.