A sodium-ion battery made by Chinese firm Hina has been found to be broadly comparable to lithium-ion batteries used by Tesla in its electric vehicles (EV).

Long-term forecasts suggest that lithium demand will continue to outstrip supply globally for the foreseeable future as it underpins many of the technologies needed for decarbonisation including EVs and renewable technology.

Since sodium is much more abundant and widely available than lithium, using it for batteries could cut raw material costs for manufacturers and reduce long-term supply chain risks. Sodium-ion batteries also perform well under load at low temperatures, making them an appealing option for both stationary power storage and mobile applications in cold climates. 

Moritz Schütte, a researcher at RWTH Aachen University in Germany, has been assessing batteries made by Hina and found that once they have been tweaked to charge more effectively at low temperatures and function better at high-energy densities, they could provide a cost-effective alternative for future EV batteries. 

“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,” Schütte said.

To assess how Hina’s batteries compare to Tesla’s, the researchers used a technique called impedance spectroscopy to measure the uniformity of 120 sodium-ion battery cells. To map out the power and energy performances of individual cells under real-life conditions, the team tested the batteries at varying currents and at temperatures from -20 °C to 45 °C. They also used X-rays to see the battery’s internal structure, then opened up the cells to measure their electrode dimensions, compositions and microstructures. 

They found that the battery uses a tabless, a double-aluminum current collector design that reduces resistance and ensures a uniform temperature distribution. It also mirrors the current design of Tesla batteries. Nevertheless, the sodium-ion battery currently has some limitations when it comes to energy density and charging at low temperatures. 

“The high‑power performance was better than one might expect from an early commercial sodium‑ion product,” Schütte said. “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 researchers also found unexpectedly high, unevenly distributed levels of copper in certain cathode regions of the battery, which “raises interesting questions about its role in performance and ageing,” said Schütte. “It will be exciting to see future sodium-ion technologies that are free of nickel and copper as well, while achieving competitive energy density.” 

Today’s commercial sodium-ion cells generally have lower energy density than the best lithium-ion cells, which will limit their usage in the short term until the technology advances.