A new study from Germany’s Federal Institute for Materials Research and Testing (BAM) has revealed that sodium-ion batteries — often seen as a sustainable and cost-effective alternative to lithium-ion technology — may require specially designed safety mechanisms before they can be deployed at scale.
The research, conducted in collaboration with the European Synchrotron Radiation Facility (ESRF) in France and the Fraunhofer Institute for High-Speed Dynamics (EMI), highlights that proven safety systems used in lithium-ion cells cannot be directly transferred to sodium-based batteries. Instead, they need to be adapted to the chemistry and mechanical design of each new system.
Putting Sodium-Ion Safety to the Test
To explore how sodium-ion batteries react to damage, researchers performed a nail penetration test — a widely recognized procedure that simulates severe mechanical failure by driving a metal pin through a cell. The test helps determine whether a battery undergoes dangerous thermal runaway reactions, such as overheating, fire, or explosion.
Using high-speed X-ray imaging at ESRF’s advanced test facilities in Grenoble, the team captured real-time footage of internal reactions inside the batteries. Three cell types were examined side by side:
- A nickel-manganese-cobalt (NMC) lithium-ion battery, commonly found in electric vehicles and portable electronics.
- A lithium-iron-phosphate (LFP) battery, favored for its high stability in stationary storage.
- A sodium-ion battery, representing an emerging alternative that uses more abundant and less costly materials.
A Surprising Reaction
The study found stark contrasts in performance. The LFP battery remained stable under stress, while the NMC cell’s built-in safety systems functioned as intended. The sodium-ion cell, however, displayed a sudden, near-explosive reaction.
Researchers determined that the cause was not the sodium chemistry itself, but rather a failure in the battery’s venting system — the component responsible for releasing excess internal pressure. In this case, the vent became blocked by other safety elements during a rapid pressure buildup, preventing controlled release and triggering a violent rupture.
Designing Safety for New Chemistries
“Our investigations show that safety mechanisms cannot simply be transferred from one battery technology to another,” said Nils Böttcher, Head of the Battery Test Center at BAM. “For new battery types such as sodium-ion cells, mechanical components like venting systems must be specifically designed and validated.”
Böttcher stressed that the findings don’t question the overall safety of sodium-ion batteries, but they underscore the need for integrated safety design — ensuring that chemical, mechanical, and thermal systems are developed in tandem.
BAM is now contributing its findings to standardization efforts and international testing protocols aimed at establishing clear safety criteria for sodium-ion technologies.
As the race to develop sustainable, lithium-free batteries accelerates, the study serves as a reminder that innovation must go hand in hand with safety engineering — especially when new chemistries promise to power the next generation of energy storage solutions.
Source: Chemeurope.com
