Risks of Transporting High Energy Battery Cells at Sea.

by | Apr 9, 2025 | Safety, Uncategorized

Risks of Transporting high energy battery cells at sea

Risks of Transporting High Energy Battery Cells at Sea.

by | Apr 9, 2025 | Safety, Uncategorized

 

Carriage of electric vehicles at sea can often create risks which sometimes go unappreciated and may even slip through the net of an active and well-founded safety management system. Electric vehicles are generally powered by lithium iron batteries. These batteries are stored in large banks within the vehicle and produce very high levels of energy required to power all the systems on the car and of course to give the car a reasonable mileage when used in full electric mode.

 

The carriage of these electric vehicles has been documented over the past few years.  Recent fires on board car ships have shown that due to their popularity and the increasing energy cells contained within the chassis themselves, the risk of fire and other hazards associated with large banks of batteries has become much higher.

Lithium-ion (Li-ion) batteries are widely used due to their high energy density and rechargeability, but they also pose significant safety risks, particularly due to thermal runaway. Here’s a breakdown of the dangers and how they relate to thermal runaway.

 

1. Thermal Runaway: The Most Critical Risk

 

Thermal runaway is a self-sustaining chain reaction that occurs when a Li-ion battery overheats, leading to further temperature increases and ultimately causing failure. It can result in fire, explosion, and toxic gas release.

How It Happens:

1. Overheating or damage (e.g., short-circuit, overcharging, external heat, or mechanical impact).
2. Breakdown of internal components (electrolyte decomposition, separator melting).
3. Exothermic reactions (release of heat and gases, increasing pressure).
4. Cascade effect—heat spreads to neighboring cells, accelerating failure.
• Consequences:
• Fire or explosion due to flammable electrolyte vapors.
• Generation of toxic gases (hydrogen fluoride, carbon monoxide, etc.).
• Rapid temperature rise (thermal runaway can reach over 1,000°C).

2. Causes of Li-ion Battery Failures

Several factors can trigger thermal runaway and other safety hazards:
• Overcharging: Can lead to excessive lithium plating, causing short circuits.
• Over-discharging: Can damage the electrodes and cause instability.
• Physical Damage: Punctures or crushing can result in internal shorts.
• Manufacturing Defects: Poor quality control can lead to internal flaws.
• External Heat Exposure: Prolonged exposure to high temperatures can degrade the battery.
3. Fire and Explosion Risks
• Li-ion batteries contain flammable electrolyte, which can ignite if exposed to a spark.
• Once ignited, Li-ion fires burn at high temperatures and are difficult to extinguish with conventional firefighting methods.
• Fires can reignite even after being put out due to residual heat.

4. Toxic Gas Emissions

• When a Li-ion battery fails, it releases dangerous gases such as:
• Hydrogen fluoride (HF): Highly toxic and corrosive.
• Carbon monoxide (CO): Can cause asphyxiation in confined spaces.
• Organic solvents: Can form explosive mixtures in air.

5. Safety Precautions

To mitigate risks, best practices include:
• Proper storage and transport: Avoid extreme temperatures and physical damage.
• Battery management systems (BMS): Prevent overcharging and over-discharging.
• Fire suppression methods: Use Class D fire extinguishers or specialized agents.
• Early warning systems: Thermal sensors and gas detection can identify risks before failure.
The emission of hydrogen – a major risk in confined spaces

The Process of Thermal Runaway

Thermal runaway occurs in distinct stages:

Stage 1: Heat Generation (Initial Trigger)

• Overcharging, overheating, or physical damage causes the battery’s temperature to rise.
• The separator (polymer membrane) inside the battery begins to weaken.

Stage 2: Breakdown of Internal Components

• Around 80–120°C (176–248°F):
• The solid electrolyte interphase (SEI) layer decomposes, generating heat.
• Lithium reacts with the electrolyte, forming flammable gas.
• Around 150–200°C (302–392°F):
• The separator melts, causing an internal short circuit.
• The electrolyte starts to decompose, producing gases like hydrogen (H₂), carbon monoxide (CO), and methane (CH₄).

Stage 3: Rapid Heat Accumulation (Thermal Runaway)

• Above 200–300°C (392–572°F):
• The cathode decomposes, releasing oxygen.
• The electrolyte completely vaporizes and ignites.
• The battery enters an unstoppable self-heating reaction.
• Above 500°C (932°F):
• The battery explodes or burns violently.
• Flames can spread to adjacent cells, causing a domino effect in battery packs.

 

 

Transporting high energy battery cells at sea

The dangers of Hydrogen Emission

 
Lithium-ion (Li-ion) batteries can emit hydrogen (H₂) under certain failure conditions. While hydrogen is not a primary gas released under normal operation, it can be produced in specific circumstances, such as thermal runaway, overcharging, or exposure to high temperatures.

How Hydrogen is Generated in Li-ion Batteries

1. Electrolyte Breakdown:
• Li-ion batteries contain a flammable organic electrolyte (typically a lithium salt like LiPF₆ dissolved in solvents such as ethylene carbonate).
• At high temperatures (~100–200°C), this electrolyte can decompose, producing hydrogen (H₂), carbon monoxide (CO), and other flammable gases.

2. Reaction with Water or Moisture:

• If moisture enters a damaged Li-ion battery, it can react with lithium-based compounds inside, leading to hydrolysis reactions that release hydrogen gas (H₂) and hydrofluoric acid (HF), a toxic and corrosive gas.
3. Thermal Runaway:
• During thermal runaway, the internal temperature of a battery rapidly rises above 200°C.
• This leads to the breakdown of battery components, producing a mix of hydrogen, methane, ethane, ethylene, carbon dioxide, and other flammable gases.
• The presence of hydrogen increases the risk of explosion, especially in confined spaces like ships, aircraft cargo holds, or battery storage containers.

3. Risks of Hydrogen Emission

• Explosion Hazard:
• Hydrogen has a low ignition energy and a wide flammability range (4–75% in air), making it highly explosive in enclosed areas.
• If a Li-ion battery emits hydrogen in a poorly ventilated space, it can form an explosive mixture with air.
• Fire Propagation:
• Hydrogen can ignite from a spark, static discharge, or high temperatures, worsening Li-ion battery fires.
• Once ignited, hydrogen burns invisibly with a very high flame temperature.
• Confined Space Danger:
• In maritime or industrial settings, hydrogen accumulation in sealed battery rooms or cargo holds can create an explosion risk.
• Proper ventilation is essential to prevent hazardous gas buildup.

4. Prevention & Safety Measures

• Gas Detection: Install hydrogen gas sensors in Li-ion battery storage areas.
• Ventilation Systems: Ensure battery compartments have proper venting to release gases safely.
• Thermal Management: Prevent overheating using battery management systems (BMS) and thermal monitoring.
• Fire Suppression: Use lithium-ion-specific fire suppression systems (such as aerosol-based or gas inerting systems) to mitigate risks.

Since electric vehicles are carried on board car ships in relatively confined spaces i.e. carriage within low deck head car decks, the accumulation of hydrogen can quickly lead to an explosion risk.

 

Hydrogen is 14% lighter than air and therefore will ultimately accumulate at the deck head. Failure of the battery pack within an electric vehicle may cause heat and or sparks to be generated and if the hydrogen mix is low enough from the deck head to come in contact with the burning battery than rapid ignition of the hydrogen will take place.

 

As the car is being transported within a relatively confined space this can lead to explosion and structural failure of the decks above and below the affected car deck. This turn, mainly due to the domino effect of thermal runway, will affect large amounts of electric vehicles. This will intensify the heat of any fire produced enabling it to spread through multiple car decks and quickly become uncontrollable by the ships crew.  Resulting in the ship needing to be abandoned, the vehicles themselves being constructive total losses and may even in an extreme case lead to either the total loss or founding of the ship.

 Please contact us info@captainbarrysadler.com

 

     

    Listen to our Hazards with Lithium Batteries on Our Maritime Education Podcast
    Author
    Steph
    Category
    Safety | Uncategorized
    Date
    April 9, 2025