The findings suggest sodium-ion technology could become a lower-cost alternative for future electric vehicles and large-scale energy storage systems. To reach that goal, however, the battery will need further improvements in low-temperature charging and energy density. Unlike lithium, sodium is abundant and readily available, making it an attractive material for reducing battery costs and supply chain concerns.

"The combination of good uniformity, high power capability, and strong low-temperature performance makes these cells attractive for stationary storage, grid services, and shorter-range or commercial vehicles where potential lower cost and resource availability matter more than maximum driving range," says Moritz Schütte, a battery researcher at RWTH Aachen University in Germany.

Comparing Sodium-Ion Batteries With Tesla Technology

To evaluate the Hina battery, Schütte and colleagues examined 120 sodium-ion cells using impedance spectroscopy, a non-destructive method that measures battery uniformity.

The researchers then tested the cells under a variety of real-world operating conditions. Performance was measured across different current levels and temperatures ranging from −20 °C to 45 °C. The team also used X-rays to examine the batteries internally before disassembling them to analyze electrode dimensions, material composition, and microscopic structural features.

One notable discovery was the battery's tabless, double-aluminum current collector design. This configuration helps reduce electrical resistance and promotes more even temperature distribution throughout the cell. The researchers noted that this design closely resembles the architecture currently used in Tesla batteries.

"We were positively surprised by how uniform the cells are," says Schütte.

Strengths and Remaining Challenges

Despite the encouraging results, the researchers identified several areas where the sodium-ion battery still trails leading lithium-ion technologies.

"The high-power performance was better than one might expect from an early commercial sodium-ion product," says Schütte. "However, for applications that require frequent charging at low ambient temperatures, appropriate thermal management or operating strategies will be important because low-temperature charging remains a clear weakness."

The team also detected unexpectedly high concentrations of copper in certain regions of the battery's cathode. In addition, the copper was unevenly distributed throughout those areas.

According to Schütte, this finding "raises interesting questions about its role in performance and aging."

"It will be exciting to see future sodium-ion technologies that are free of nickel and copper, as well, while achieving competitive energy density," he said.

Why Sodium Could Matter for Future Batteries

Because sodium is far more abundant and widely available than lithium, manufacturers could potentially lower raw material costs while reducing long-term supply chain risks.

Sodium-ion batteries also maintain strong performance under load in cold conditions, making them attractive for stationary energy storage systems and mobile applications operating in colder climates.

"However, today's commercial sodium-ion cells generally have lower energy density than the best lithium-ion cells, and the technology is less mature overall," said Schütte.

Next Steps for Sodium-Ion Research

The researchers plan to focus on improving charging performance at low temperatures, with the goal of enabling safer and more efficient charging below 0°C.

Additional work will also explore ways to optimize the materials used in sodium-ion batteries.

"Advances in hard-carbon anodes and electrolyte formulations may be especially promising," he said.

The study was supported by the Federal Ministry of Research, Technology, and Space and the Federal Ministry for Economic Affairs and Energy.