Researchers from the University of Chicago and partners have made a breakthrough in sodium-based all-solid-state batteries that perform well even in cold conditions, which is a key hurdle for alternatives to lithium chemistries, tells Tech Xplore.
The main findings include:
- What the problem was: Solid-state batteries are desirable for their safety and power density, but sodium versions have struggled at moderate-to-low temperatures. Their performance drops when things aren’t warm.
- What they did: The team developed a new solid electrolyte based on sodium closo-hydridoborate in a metastable form. This material has much higher ionic conductivity (how easily sodium ions move through it) than previous versions; over 10 times higher than past hydrated borates, and thousands of times better than some precursor materials.
- How: They used a heating-then-rapid cooling process to trap a metastable crystal structure, then paired that electrolyte with a thick cathode (O₃-type) coated with a chloride-based solid electrolyte. Thick cathodes are harder to do well because they tend to include more “dead weight” (inactive material), but here they managed to preserve performance.
- What this achieves: The design keeps good performance from room temperature down through subzero, narrowing the gap with lithium solid-state batteries. That’s promising for applications in electric vehicles or grid storage where batteries must work in cold climates.
- Limitations and outlook: This is still lab scale. Scaling up will require solving practical manufacturing challenges. But because the technique (metastable electrolyte + thick cathode) uses known methods, it’s more likely to be translatable into real devices than wholly new, exotic approaches.
This work pushes sodium solid-state batteries significantly closer to being usable, especially in colder environments. If further developed, they could offer a cheaper, more abundant, and less damaging complement, or alternative, to lithium options.