Can scandium improve the lifespan of sodium-ion batteries? More than 90% capacity retained after 300 cycles

Japanese researchers from the Tokyo University of Science have developed an innovative method for stabilizing cathodes in sodium-ion batteries using scandium. Thanks to a special coating, the new battery retained as much as 91.2% of its initial capacity even after 300 charge–discharge cycles.

Bulk doping vs surface coating

Sodium-ion batteries are considered a cheaper and more readily available alternative to lithium-ion cells. However, their main weakness is the rapid capacity degradation of the cathode (NNMO) during operation. A team led by Professor Shinichi Komaba tested two approaches using scandium ions:

• Bulk doping – incorporating scandium into the material’s crystal structure stabilizes it from within and reduces changes in cathode volume during battery operation.
• Surface coating – creating a protective scandium-based layer on the surface of the particles suppresses undesirable side reactions at the interface with the electrolyte.

In full-cell tests using a hard-carbon anode, the variant with 8% bulk doping retained 71.4% of its capacity after 300 cycles, while the surface coating achieved an impressive 91.2%. By comparison, the pure, unmodified cathode retained just 18.6% after 100 cycles.

Technological synergy could pave the way for commercialization

Detailed structural studies using X-ray diffraction and density functional theory (DFT) calculations confirmed that combining the two methods produces a synergistic effect.

According to the authors of the study, published in the prestigious journal Small, simultaneously coating and doping cathodes with scandium could significantly extend the lifespan of sodium-ion cells. This could accelerate their widespread adoption in stationary energy storage systems and electric vehicles.