Potential Hazards Facing Emergency Responders for Lithium Ion Batteries
Rechargeable lithium-ion batteries are found in electrical devices such as phones, computers, toys and cordless appliances such as vacuum cleaners. They are commonly used in gardening and home improvement tools like whipper snippers and drills. These batteries are almost always used in hoverboards, ebikes and scooters.
Lithium-ion battery failures can occur due to imperfections in the construction of the cell or through abuse. Abuse of cells, packs or modules can be caused by impact, such as dropping or collisions in transit, piercing from tooling, shorting, over charging and being exposed to higher or lower temperatures than those that the battery is designed for. Once a battery has been damaged it may take some time to develop symptoms such as swelling or heating.
Lithium-ion batteries can react in a variety of different ways depending on the type of fault, the area that is damaged, state of charge and chemistry of the affected battery. The following scenarios may occur:
• Damaged cells may vent / smoke without ignition.
• Fires may occur when the electrolyte ignites.
• A jet of flame and burning material being ejected from a single point can create a flare.
• The battery may burn or create a fireball, depending on the failure mode.
• The battery may also explode.
Lithium-ion cells can transition between reactions. Venting cells can catch fire, then explode, they may also vent then explode without catching fire. This smoke is generally made of hydrogen, carbon monoxide, carbon dioxide and a range of hydrocarbons although the exact composition of the smoke is dependent on the chemistry used.
Once a battery cell has failed the heat generated can cause other cells in close proximity (stored together or together in modules and packs) to fail, resulting in a chain reaction (also known as the snowball effect or runaway).
The following YouTube video from Professor Paul Christensen's lecture in the UK is an interesting one to watch. It addresses the above quite well. It starts at about 6min 30s and goes on till about 41m50s.