In response to the growing risks associated with the maritime transport of lithium-ion cells and batteries, the following guidance for shipping lithium-ion cells and batteries in containers.
Lithium-ion cells are the core components of batteries and come in various forms, as they are widely used in portable electronics and electric vehicles because they can efficiently store and release energy through the movement of lithium ions between positive and negative electrodes.
However, due to their chemical properties, lithium-ion cells and batteries are classified as dangerous goods and must be handled with care.
Released against a backdrop of rising concern, the guidance comes as battery-related incidents at sea become both more frequent and more severe.
A key hazard is thermal runaway, a chain reaction that can result in intense fires, the release of toxic gases and even explosive force. These fires are particularly difficult to extinguish and may reignite days or even weeks after the initial incident.
According to the Nordic Association of Marine Insurers (Cefor) in its 2025 year-end ocean hull report, fires remain a major source of marine losses. The report highlights an increase in severe fire incidents involving both container vessels and car/RoRo ships.
As a result, the marine industry, including insurers, has become increasingly concerned about the rising number of onboard fires, particularly in cargo holds and engine rooms.
What is a Lithium-ion cell?
Lithium-ion cell is a rechargeable electrochemical cell in which both the positive and negative electrodes are intercalation compounds. Lithium exists in an ionic or quasi-atomic form within the electrode material. Lithium polymer cells using lithium-ion chemistry are regulated as lithium-ion cells or batteries.
Lithium-ion cells and batteries are classed as dangerous goods because of several hazardous properties.
- Fire Hazard: Flammable electrolytes can ignite if damaged or overheated, triggering thermal runaway reactions that lead to fires or explosions.
- Chemical Reactivity: Reactive materials may explode or catch fire if punctured or short-circuited.
- Toxic Emissions: Fires release harmful gases such as hydrogen fluoride (HF), which are toxic and corrosive.
- Explosion Risk: Internal pressure buildup can cause rupture or explosive vapour clouds.
- Electrical Hazard: Short circuits or mishandling can lead to burns, sparks, or fires.
- Environmental Risk: Improper disposal can contaminate soil and water, causing environmental harm.
Key risks during transport
These factors increase the risks involved in the carriage of lithium-ion cells and batteries:
– Packing not consigned in compliance with the IMDG Code.
– Packing into containers other than in accordance with the CTU Code.
– High temperature inside container(s) during transport
– Cell or battery not in compliance with UN 38.3
Packing the Cargo Transport Unit (CTU)
CINS does not recommend co-loading lithium-ion cells or batteries with other Dangerous Goods, except co-loading with each other.
To ensure adequate packing is carried out and there is no mixed loading, Shippers must pack and stuff in accordance with IMDG code/CTU code and shipping lines should conduct random checks to ensure compliance.
To assist firefighting and to mitigate risks, it is recommended that cargo stuffing should keep to:
- a minimum 30cm gap between the top of cargo and the container ceiling.
- a minimum 30cm gap between the cargo and the container doors.
- ensuring that the packaging is not in direct contact with the container walls.
It is recommended to stow and secure cargo units within a container without any free gaps. Such gaps, unavoidable during stowage, shall be filled out completely by suitable blocking material. Blocking material can for example be hard boards for smaller gaps, empty pallets for medium gaps or measure made blockings for greater gaps.
The guidelines offer practical safety advice for shipping companies, operators, and carriers handling lithium-ion batteries classified under UN 3480 and UN 3481 in Cargo Transport Units (CTUs).
By clearly outlining key risks and mitigation steps, the guidelines aim to help the maritime industry better control hazards and reduce the risk of costly and dangerous incidents during sea transport.