A new report from Tokyo University of Science in Japan reveals how new materials can dramatically improve the durability and performance of sodium-ion batteries (SIBs) through two distinct mechanisms—bulk doping and surface coating.

A research team led by Professor Shinichi Komaba and Associate Professor Shinichi Kumakura from the Department of Applied Chemistry at Tokyo University of Science investigated how incorporating scandium, specifically Sc3+ , into cathodes based on a sodium-ion chemistry called NNMO. The study showed scandium doping can stabilize the battery's bulk crystal structure, while scandium coating can suppress surface degradation, offering two complementary strategies for boosting battery life and performance (Fig. 1).

Tests revealed that scandium modification dramatically improved capacity retention after 100 charge-discharge cycles from 18.6% for undoped electrodes to 67.8% with scandium doping and 75.4% with scandium coating. The other highlight is that, in full sodium-ion cells, the scandium-coated cathode retained 91.2% of its initial capacity after 300 cycles, representing a substantial improvement in long-term battery durability, the team said.

The research could be a boon to battery manufacturers, giving them a way to supply lower-cost, longer-lived SIB cells. Part of SIB's rising popularity is due to the much greater abundance of sodium compared to lithium. As a result, SIBs offer the potential to provide much lower cost per kW/h of capacity relative to today's lithium-ion (Li-ion) batteries. In addition, SIBs could also offer better safety and low-temperature performance.

While it’s still early, SIBs are already being commercialized in stationary, grid-connected battery energy storage systems (BESSs) and backup power applications, where they probably have the best of chance of beating Li-ion batteries. They are also breaking through in applications ranging from portable electronics to electric vehicles (EVs).

The report, titled "Scandium doping and coating for improving O3-NaNi1/2Mn1/2O2 electrode in sodium battery,” was published in “Small”. a journal for micro/nano-technology, which can be accessed at this link: 10.1002/smll.75049.