The International Maritime Dangerous Goods (IMDG) Code, published by the International Maritime Organization (IMO), provides comprehensive regulations for the safe transportation of dangerous goods by sea, including lithium-ion and lithium-metal batteries. These provisions are critical for minimizing risks such as thermal runaway, fire, and environmental hazards during maritime shipping. The code categorizes batteries based on their chemistry, size, and risk profile, with specific requirements for packaging, stowage, segregation, and emergency response.
**Classification and Identification**
Lithium batteries fall under Class 9 (Miscellaneous Dangerous Goods) in the IMDG Code. They are further subdivided into:
- UN 3090: Lithium-metal batteries (primary, non-rechargeable)
- UN 3091: Lithium-metal batteries contained in or packed with equipment
- UN 3480: Lithium-ion batteries (rechargeable)
- UN 3481: Lithium-ion batteries contained in or packed with equipment
Small batteries (≤ 20 Wh per cell or ≤ 100 Wh per battery) may qualify for limited quantity exemptions, reducing some packaging and labeling requirements. Large batteries exceeding these thresholds must comply with full dangerous goods regulations.
**Container and Packaging Requirements**
The IMDG Code mandates robust packaging to prevent short circuits, damage, and movement during transit. Key requirements include:
- Inner packaging: Non-conductive, cushioned material to separate cells or batteries.
- Outer packaging: Rigid, weather-resistant containers meeting UN performance standards (e.g., UN 4G for fiberboard boxes).
- Marking and labeling: Packages must display the Class 9 hazard label, lithium battery handling mark (for exempted small batteries), and proper shipping name/UN number.
- State of charge (SOC): Lithium-ion batteries must be shipped at ≤ 30% SOC unless specifically approved for higher states.
For large battery shipments (e.g., EV batteries or grid storage units), additional structural integrity checks are required. Batteries must be secured within containers to prevent shifting, with non-conductive barriers to avoid contact with metal surfaces.
**Stowage and Segregation Rules**
The IMDG Code specifies stowage categories based on battery type and risk:
- Stowage Category A: Permitted on all vessel types (e.g., small lithium batteries under exemption).
- Stowage Category B: Restricted from certain spaces (e.g., large lithium batteries must avoid direct sunlight or heat sources).
Segregation rules prevent interactions between incompatible goods:
- Lithium batteries must be separated from flammable liquids (Class 3), oxidizing substances (Class 5.1), and explosives (Class 1).
- Vertical segregation: Batteries cannot be stowed below decks if incompatible goods are stored above them.
**Emergency Response Protocols**
Thermal runaway or fire involving lithium batteries requires specialized handling due to the risk of reignition and toxic gas emissions. The IMDG Code outlines:
- Fire suppression: Use copious amounts of water (not dry chemical or CO2 extinguishers) to cool batteries and prevent propagation.
- Ventilation: Toxic fumes (e.g., hydrogen fluoride) necessitate crew use of self-contained breathing apparatus (SCBA).
- Overboard jettisoning: As a last resort, cargo may be dumped at sea if it poses an imminent threat to the vessel.
Crew training is mandatory, including drills for battery-related incidents. Vessels carrying large quantities of lithium batteries must have dedicated firefighting equipment and emergency plans filed with port authorities.
**Port Authority Oversight**
Ports play a critical role in enforcing IMDG compliance:
- Pre-shipment inspections: Verify documentation (e.g., Dangerous Goods Declaration, test summaries) and packaging integrity.
- Stowage checks: Confirm segregation and securing of battery cargo before departure.
- Incident reporting: Ports must notify the IMO of any battery-related accidents during loading or unloading.
Differences between small and large shipments are significant:
- Small batteries (exempted): Often consolidated in general cargo with minimal oversight.
- Large batteries: Require dedicated container slots, additional firefighting provisions, and prior notification to port and vessel operators.
The IMDG Code is updated biennially to reflect technological advancements and incident learnings. Recent revisions include enhanced testing standards (UN 38.3) and stricter labeling for lithium-metal batteries. Compliance ensures safe global trade of batteries while mitigating environmental and operational risks.
Maritime shipping remains a dominant mode for battery logistics due to cost-effectiveness for bulk transport. Adherence to the IMDG Code is not optional; violations can result in cargo rejection, fines, or even vessel detention. Stakeholders—manufacturers, shippers, and port authorities—must collaborate to maintain safety without disrupting supply chains. Future amendments may address emerging technologies like solid-state batteries, but current provisions provide a robust framework for risk management.