New Batteries, New Rules for the Open Road

Federal safety research on sodium-ion batteries is reshaping how hazmat road shippers classify and handle next-generation energy cargo

7 Mar 2026

When battery chemistry changes, so does everything else. Federal regulators are now catching up to a new class of energy storage technology, and the US hazardous materials transport sector is bracing for a significant overhaul in how it classifies, packages, and moves battery freight.

On February 10, 2026, the Pipeline and Hazardous Materials Safety Administration published a proposed rule under docket HM-215R, introducing transport provisions for sodium-ion batteries while aligning US hazmat regulations with updated UN standards and the 2025-2026 ICAO Technical Instructions. The proposal is not a bureaucratic housekeeping exercise. It is a direct response to new science.

Researchers at UL Research Institutes' Electrochemical Safety Research Institute have been stress-testing commercially available sodium-ion cells, and what they found is notable: unlike their lithium-ion counterparts, sodium-ion batteries show no catastrophic thermal runaway under standard test conditions. They can also be transported at zero percent state of charge without damage, a logistical advantage that ground shippers managing high-volume freight will find meaningful. Those findings are now headed to federal stakeholders at PHMSA's Research, Development and Technology Forum, scheduled for March 31 through April 2 in Washington, DC.

The regulatory mechanics follow the science closely. PHMSA's proposal would create two new Hazardous Materials Table entries: UN 3551 for standalone sodium-ion batteries with organic electrolyte, and UN 3552 for batteries contained in or packed with equipment. Both would fall under the same framework currently applied to lithium-ion cells. The rule also proposes capping state of charge at 30 percent or less for certain battery types shipped by air, a restriction grounded in existing ground transport risk research.

For compliance professionals, the checklist is already growing. Classification workflows, packaging instructions, and emergency response documentation will all need updating before any final rule takes effect. The comment period on HM-215R closes April 13, 2026, leaving road carriers and dangerous goods practitioners a narrow window to weigh in on rules that will govern a fast-expanding slice of American freight.

Battery chemistry is moving faster than the rulebook can follow. That gap is exactly what PHMSA is now trying to close.