Solid-state batteries – BAM develops a powerful alternative to lithium-ion batteries
Oliver Perzborn , Communications and Marketing Department,
Federal Institute for Materials Research and Testing (BAM)
Berlin, May 15, 2025. Researchers at the Federal Institute for Materials Research and Testing (BAM) have developed an innovative approach to make solid-state batteries more powerful and suitable for everyday use. Their goal: batteries that charge faster, last longer, and are more sustainable than conventional lithium-ion batteries. A new solid electrolyte could pave the way for a pioneering battery technology.
The performance limits of conventional lithium-ion batteries have been reached: Their anodes, usually made of graphite, can only store a limited number of ions. An alternative is anodes made of pure lithium or the more sustainable and cheaper sodium – they could increase energy density by up to 40 percent. However, to operate them safely, a solid rather than a liquid electrolyte is needed. A key problem: At the interface between the solid anode and the solid electrolyte, contact losses and voids can occur, rendering the battery unusable. One possible solution: a partially liquid anode.
Revolution through liquid alkali metal anodes
Gustav Graeber, battery materials expert at Humboldt University Berlin and visiting scientist at BAM, explains:
In a study, we were able to show that a liquid alkali metal anode is 100 times more powerful than conventional graphite anodes,
“So far, however, this technology can only be used at 250 degrees Celsius. Our goal is to transfer its advantages to room temperature.”
To achieve this, the research team is experimenting with potassium additives that lower the melting point of the anode. The challenge: many common solid electrolytes are not stable enough towards potassium.
New solid electrolyte as a key technology
The solution could lie in a special solid electrolyte based on sodium superionic conductors (NASICON). These materials offer high ionic conductivity at room temperature and are simultaneously chemically stable towards potassium – especially when mixed with hafnium. However, hafnium is rare and expensive. In the NASICON project, Graeber and his interdisciplinary team of BAM experts are therefore looking for alternative additives that are equally powerful but more sustainable and widely available. The most promising candidates are being tested directly in sodium batteries.
Graeber, says:
Our research project is a crucial step towards high-performance batteries that are more sustainable, cheaper, and more efficient,
“Solid-state sodium batteries could drastically reduce charging times and significantly improve the performance of mobile and stationary energy storage systems – an important contribution to decarbonization.”
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