Batteries power countless devices, from smartphones to electric vehicles. While generally safe, concerns about battery incidents, including fires or explosions, are valid given their widespread use. Understanding their mechanisms and preventive measures can help mitigate potential risks. This article explores battery incident causes, prevention, and appropriate responses.
How Batteries Can Explode
A battery “explosion” refers to a rapid, uncontrolled energy release, often involving fire, smoke, and material expulsion. This stems from thermal runaway. Thermal runaway occurs when a battery cell generates more heat than it can dissipate, leading to a self-accelerating cycle that destabilizes internal chemistry. Once internal temperature reaches a critical point (e.g., 60°C), the battery can release large amounts of flammable, toxic gases. This rapid temperature increase and gas buildup can burst the casing, igniting gases and rapidly propagating fire across other cells.
Lithium-ion batteries, with high energy density and flammable liquid electrolyte, are particularly susceptible to thermal runaway. The electrolyte facilitates ion movement, but if compromised, this organic solvent can ignite. The positive electrode (cathode) also contains oxygen, which can be released under stress, fueling a fire even without external oxygen. While violent explosions with projectile fragments are rare, rapid fire onset and venting of hot, toxic gases are extremely hazardous.
Triggers for Battery Incidents
Several factors can initiate thermal runaway in batteries. Overcharging is a common trigger, where supplying too much voltage or current beyond the battery’s capacity generates excessive heat. This can cause the electrolyte to heat up and potentially ignite. Physical damage, such as puncturing, crushing, or severe impacts, can compromise the battery’s internal structure, leading to an internal short circuit. This damage can cause a rapid discharge of energy and significant heat generation.
Extreme temperatures also play a role. Storing batteries in very high ambient temperatures, like a hot car, accelerates internal chemical reactions and can destabilize them. Conversely, charging lithium-ion batteries below 0°C can cause lithium metal buildup on the negative electrode, potentially leading to a short circuit. Internal or external short circuits, whether from manufacturing flaws or external contact with metal objects, can cause a sudden and uncontrolled energy release and heat buildup. Manufacturing defects, though uncommon, can introduce impurities or flaws in the battery’s construction that may lead to internal short circuits and eventual thermal runaway. Incorrect or unapproved chargers can supply mismatched voltage or current, bypassing safety mechanisms and contributing to overcharging and overheating.
Preventing Battery Hazards
Minimizing the risk of battery incidents involves adhering to safe handling and charging practices. Always use the manufacturer-approved charger for your device or battery. Uncertified chargers may lack safety features. Do not leave devices continuously charging overnight; prolonged overcharging can contribute to battery degradation and overheating.
Protect batteries from physical damage; avoid dropping, puncturing, or crushing them, as this can breach their internal components and lead to short circuits. Store batteries in a cool, dry place at room temperature, away from direct sunlight or extreme heat. High temperatures can cause the fluid inside batteries to evaporate or accelerate chemical reactions. When storing loose batteries, keep them in original packaging or a plastic container. Cover terminals with tape to prevent accidental short circuits.
Inspect batteries for swelling, bulging, excessive heat, or unusual odors or noises. If present, discontinue use immediately. Dispose of damaged or old batteries properly at certified recycling centers or household hazardous waste collection points. Never place them in regular trash or recycling bins.
What to Do During a Battery Incident
If a battery shows signs of overheating, swelling, smoke, or fire, immediate action is necessary. If safe, disconnect the device from its power source and move it to a non-flammable surface (e.g., concrete or tile), away from combustible materials. Evacuate the area, as battery fires can produce toxic gases like hydrogen fluoride and carbon monoxide. Do not touch a hot or burning battery due to burn risk and chemical exposure.
For small lithium-ion battery fires, a standard ABC or dry chemical extinguisher can be used. However, these fires are difficult to extinguish because the battery generates its own oxygen and heat.
Water can cool the battery and prevent fire spread, but it does not stop the thermal runaway reaction. Specialized extinguishers with Aqueous Vermiculite Dispersion (AVD) cool and encapsulate burning cells, preventing re-ignition.
If the fire is significant or uncontrolled, immediately call emergency services and follow their instructions. Allow trained professionals to manage larger battery fires, as they require specialized tactics and equipment.