Researchers at Germany’s Federal Institute for Materials Research and Testing (BAM) have developed a new sodium super-ionic conductor (NASICON) electrolyte that could enable more stable, high-performance solid-state batteries operating at room temperature. The breakthrough may improve safety and reduce costs compared to current lithium-ion technology.
The BAM team, led by visiting researcher Gustav Graeber, is working to overcome the limitations of traditional lithium-ion batteries, which rely on graphite anodes with limited ion storage. Switching to metallic lithium—or more readily available sodium—could increase energy density by up to 40%, but solid-state batteries require compatible solid electrolytes to avoid void formation at the anode-electrolyte interface.
To address this, the researchers are exploring a liquid alkali-metal anode that has demonstrated energy output up to 100 times higher than conventional graphite. However, such performance has only been achieved at elevated temperatures around 250°C. To reduce the operating temperature, BAM has added potassium to the anode to lower its melting point, introducing new challenges for electrolyte stability.
The NASICON materials, especially when doped with elements like hafnium, have shown strong ion conductivity at ambient conditions and chemical tolerance to potassium. Due to hafnium’s scarcity and high cost, the team is now testing more earth-abundant dopants to replicate its stabilizing properties. Promising compositions are already being cycled in early-stage sodium battery prototypes.
If successful, the technology could pave the way for solid-state sodium batteries in consumer electronics, electric vehicles, and grid storage. The shift to sodium—abundant and less geopolitically constrained than lithium or cobalt—could also contribute to a more sustainable battery supply chain.
Source: BAM