At a time when sustainable energy storage is becoming increasingly important, various battery technologies are taking centre stage. Two promising solutions are the sodium-ion battery and the redox flow battery. Both offer specific advantages, but which is the better choice? In this article, we compare the two technologies and show why the sodium-ion battery is considered a promising alternative.
How do they work – A Comparison
Sodium-ion (salt) batteries store energy using sodium ions as charge carriers, which move back and forth between the cathode and anode in an organic electrolyte. These batteries do not require scarce raw materials such as lithium or cobalt. Thanks to the high availability of sodium, they offer a sustainable and cost-effective alternative to conventional lithium-ion batteries.
Redox-Flow-Batteries work with liquid electrolytes that are stored in external tanks. The energy is released through chemical reactions within the cell by pumping it through a membrane. This technology is characterised by its scalability and is particularly suitable for stationary storage applications.
Technology comparison: sodium-ion vs. redox flow batteries
| Properties | Sodium-Ion Battery | Redox Flow Battery |
| Safety | High level of safety thanks to available materials | Safe technology, but use of liquid, potentially toxic electrolytes |
| Energy Density | 200-350 Wh/l | 15 – 80 Wh/l |
| Charing speed | Very fast (1- 10 C) | Slow (< 0,5 C) |
| Voltage Range | 1,5–4 V | 1,0–2,2 V |
| Efficiency | 90-95 % | 50 – 80% |
| Operating temperature | Wide temperature range | Limitations at low temperatures |
| Costs | Cost-effective materials and production | Higher acquisition costs due to complex systems |
| Environmental friendliness | Sustainable raw materials, low CO₂ footprint | No rare materials, but electrolytes such as vanadium oxide, sodium bromide, polysulphide bromide, zinc bromide |
Anwendungsbereiche
- Redox flow batteries are ideal for large, stationary energy storage systems such as grid stabilisation or industrial applications, as their scalability enables a high storage capacity.
- Sodium-ion (salt) batteries are suitable for both stationary and mobile applications due to their higher energy density, high level of safety and lower costs.
Conclusion
While redox flow batteries score with their unlimited scalability, sodium-ion batteries offers decisive advantages in terms of energy density, charging speed, temperature tolerance, cost-effectiveness and environmental friendliness, making it the preferred choice for future-proof energy storage solutions.
The decision for the right technology ultimately depends on the specific requirements – redox flow could continue to play a role for large-scale stationary storage systems, while sodium-ion batteries are becoming increasingly attractive as a versatile and cost-effective solution for the broad market.
