Much work has gone into refining sodium-ion battery cathodes to their optimum point. While their corresponding anodes have been receiving less attention. Researchers at Federal Institute for Materials Research and Testing in Germany decided to address this issue, by developing core shell anodes for sodium-ion batteries.
Why the Need for Core Shell Anodes Now?
Anodes have a very important role in batteries. They receive external electricity, which they store for future use. More of this energy is lost to the system in sodium-ion batteries, than is the case with lithium-ion batteries. In other words, sodium-ion’s coulombic efficiency reduces at a higher rate, especially during the first charge.
This capacity loss in sodium-ion batteries occurs due to a chemical reaction, between the anode and the electrolyte during manufacture:
- Molecules of electrolyte break down and penetrate the anode’s surface.
- These decomposed molecules reduce the area for sodium ion storage.
- This continues until an autonomous film forms on the anode surface.
The German researchers improved the initial sodium-ion storage capacity by a factor of four in their laboratory. Their solution involved introducing revolutionary core shell anodes for sodium-ion batteries, thereby preventing the ‘electrolyte molecule invasion’.
More About the Modified Sodium-Ion Anode
Battery anodes are typically porous materials like graphite, that readily attract ions. The German researchers added a lining to their experimental anode that only allowed sodium ions through.
This innovation kept the larger electrolyte molecules at bay, previously causing the undesirable side reaction. This meant the anode retained more of its original storage capacity over initial, and subsequent charging cycles.
Interesting Engineering confirms that the initial coulombic efficiency in the prototype battery was an amazing 82%. This compares well with lithium-ion batteries, and removes an impediment to sodium-ion commercialization.
More Information
Coulombic Efficiency in Batteries Unpacked
Solid Electrolyte Membranes Cut SSB Cost
Preview Image: How Core Shell Anodes Work
