BAM Study Flags Safety Gaps in Promising Sodium-Ion Batteries
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 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
Cracking the Code on Lithium Battery Safety
New research reveals hidden risks in solid-state designs — and a path toward safer, longer-lasting batteries. They’re small, powerful, and packed with potential — but lithium batteries still have one explosive problem: dendrites. These tiny, needle-like metal structures can grow inside a battery, short-circuit it, and in the worst cases, cause fires or explosions. Until now, scientists believed they had a solution. Solid-state batteries, especially those using polymer-based electrolytes, were thought to be the ultimate fix — stable, solid, and far less flammable than liquid-based designs. But a team at the Technical University of Munich (TUM) has just discovered something that could change that narrative. Their research shows that dendrites can form not only at the electrodes — where they were expected — but also within the polymer electrolyte itself. That’s the very material meant to prevent these dangerous growths. “Our measurements show that dendrite growth can also occur directly inside the polymer electrolyte — in the very material designed to stop it,” says Fabian Apfelbeck, a physicist pursuing his doctorate at TUM and lead author of the study. This revelation could reshape how scientists approach solid-state battery design. To uncover this hidden process, the TUM team used a nanofocus X-ray technique at the German Electron Synchrotron (DESY) in Hamburg. With an X-ray beam just 350 nanometers wide — roughly 200 times thinner than a human hair — they watched structural changes unfold inside a working battery for the first time. The finding surprised even seasoned researchers. “We’ve long assumed dendrites only grow at the interface between electrode and electrolyte,” explains Prof. Peter Müller-Buschbaum, who leads TUM’s Chair of Functional Materials. “Seeing them form deeper inside the material challenges that assumption completely.” Understanding where dendrites form — and why — is a critical step toward creating safer, longer-lasting, and more efficient solid-state batteries. With this knowledge, researchers can now focus on developing electrolytes that stop internal crystallization before it starts. The study, “Local crystallization inside the polymer electrolyte for lithium metal batteries observed by operando nanofocus WAXS,” was published in Nature Communications in 2025.
