Flooding Sparks Fire Risk in EV Batteries from Saltwater

In the aftermath of a hurricane, rescue workers race against time to clear debris and save lives. Yet, amid the chaos, a new hazard has emerged: electric vehicles (EVs) bursting into flames. These incidents are not random accidents but the result of a hidden threat—saltwater intrusion into lithium-ion batteries. What causes such dangerous reactions, and how can future disasters be prevented?

Recently, Hurricane Ian devastated Florida and the southeastern United States, causing widespread destruction and flooding. During recovery efforts, responders encountered multiple EV fires in vehicles powered by lithium-ion batteries. Investigations revealed that exposure to saltwater was the primary cause. Many vehicles had been submerged in floodwaters, and saltwater exposure dramatically degrades lithium-ion battery performance, triggering chemical reactions that pose extreme fire risks. Vehicle registration records show that over 7,000 EVs in Florida's Lee County alone may have been affected—a staggering number that underscores the severity of this emerging threat.

Lithium-ion batteries consist of a cathode, anode, electrolyte, and separator. The electrolyte facilitates lithium-ion movement between electrodes, while the separator prevents direct contact between the cathode and anode to avoid short circuits. Saltwater, particularly seawater, is highly conductive and corrosive. When it infiltrates a lithium-ion battery, it initiates a chain reaction that can lead to catastrophic failure.

• Electrolyte Decomposition: Chloride ions in saltwater react with the electrolyte, causing it to break down and release gases and heat. Gas buildup increases internal pressure, potentially leading to battery swelling or explosion. Meanwhile, heat accelerates chemical reactions, creating a dangerous feedback loop.
• Electrode Corrosion: Chloride ions corrode cathode and anode materials, compromising the battery's structural integrity. Corrosion reduces capacity, increases internal resistance, and heightens instability.
• Separator Failure: Saltwater degrades the separator's insulating properties. If the separator fails, electrodes may contact each other directly, causing a short circuit and intense heat generation.
• Short-Circuit Risk: Saltwater's conductivity can create unintended current paths between electrodes, releasing energy rapidly and igniting fires.

Given the extreme risks posed by damaged lithium-ion batteries, vessels, ports, and shippers must exercise heightened caution to prevent compromised EVs from being loaded onto commercial ships. The U.S. Coast Guard's Safety Alert 01-22 emphasizes that flooded or saltwater-exposed EVs should be treated as potential fire hazards and handled with extreme care.

To mitigate risks, the Coast Guard urges stakeholders to adopt the following measures:

1. Review Vehicle Transport Regulations: Thoroughly examine requirements under the Hazardous Materials Regulations (49 CFR) and the International Maritime Dangerous Goods (IMDG) Code . All lithium batteries are classified as hazardous materials, regulated by the Pipeline and Hazardous Materials Safety Administration (PHMSA). Compliance with the Shipper’s Guide for Lithium Batteries is mandatory.
2. Assess Additional Requirements for Damaged Batteries: Consult PHMSA’s Safety Advisory Notice on transporting damaged or defective lithium batteries. The IMDG Code’s Special Provision 376 mandates approval from PHMSA or the Coast Guard before shipping compromised batteries.
3. Maintain Vigilance: Ensure damaged EVs are not loaded onto vessels, stored in port facilities, or sealed in containers. All personnel must adhere to strict safety protocols.

While improved handling and regulations are essential, long-term solutions lie in advancing battery technology. Promising developments include:

• Solid-State Batteries: Replacing liquid electrolytes with solid alternatives could significantly reduce fire risks.
• Advanced Electrolytes: Non-flammable, heat-resistant electrolytes may enhance battery stability.
• Enhanced Battery Management Systems (BMS): Smarter monitoring algorithms could detect abnormalities earlier.
• Structural Improvements: Reinforced designs may better withstand environmental stresses.

As EV adoption grows, addressing these safety challenges will require collaboration across industries, regulators, and manufacturers. Only through proactive measures can the promise of sustainable transportation be realized without compromising public safety.