Sodium-ion batteries are gaining attention as a cheaper and more eco-friendly alternative to traditional lithium-ion batteries.
Since sodium is the sixth most common element on Earth, these batteries could help reduce costs and improve availability, especially as the demand for clean energy and electric vehicles continues to grow.
One of the biggest challenges in making sodium-ion batteries last longer and work better lies in improving the materials used inside them—particularly the cathode.
A material called sodium manganese oxide (NaMnO₂) has shown promise, especially in a crystal form known as the β-phase.
However, making this version of NaMnO₂ is tricky and often leads to flaws in its structure called stacking faults.
These flaws cause the battery to lose power quickly, making it less useful in real-world applications.
Now, scientists from the Tokyo University of Science, led by Professor Shinichi Komaba, have found a clever solution: adding a small amount of copper to the mix.
Their research shows that copper helps stabilize the β-phase of NaMnO₂ and greatly reduces the number of stacking faults. This improvement leads to batteries that last much longer and hold their charge better over time.
The team created several samples of copper-doped sodium manganese oxide, each with a different amount of copper.
They found that a sample with about 12% copper (called NMCO-12) had almost no stacking faults and maintained excellent performance over 150 charge-discharge cycles, with no loss in capacity.
In contrast, the undoped version lost power quickly after just 30 cycles.
With the stacking faults out of the way, the researchers were able to observe how the internal structure of the battery changed as sodium ions moved in and out during use.
They discovered a new type of movement in the manganese oxide layers that could only be seen in the pure β-phase. This discovery could lead to a deeper understanding of how to design better battery materials.
What makes this work especially exciting is its potential to support large-scale energy storage, electric vehicles, and everyday electronics like smartphones—all without relying on expensive or hard-to-find materials like lithium. Manganese and sodium are both more widely available and less costly.
This breakthrough also supports the global push for affordable and clean energy, as outlined in the United Nations Sustainable Development Goals. By making batteries more stable and cost-effective, this research brings us one step closer to a more sustainable energy future.
