Lithium-ion battery failure and swelling¶

Rechargeable lithium-ion and lithium-polymer (LiPo) batteries power modern smartphones, laptops, tablets, power banks, and cordless tools. When these batteries suffer physical damage, manufacturing defects, aging, or electrical stress, they can degrade rapidly. This degradation leads to swelling, toxic off-gassing, and intense chemical fires known as thermal runaway.

This guide provides immediate instructions to protect yourself when a battery shows warning signs or begins to burn.

Do this now¶

1. Unplug the charging cable immediately from the wall receptacle or charger.
2. Turn off the device if the screen is responsive and you can do so safely without pressing hard on the casing.
3. Do not squeeze, puncture, drop, or bend a swollen battery or device under any circumstances.
4. Isolate the device on a non-combustible surface, such as concrete, tile, or inside a heavy metal pot away from rugs, wooden furniture, and curtains.
5. If the device emits smoke, hissing sounds, or sparks, evacuate everyone from the room immediately and call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom).

Warning signs of rechargeable battery failure¶

Lithium battery failures often begin with subtle physical and electrical symptoms before escalating into hazardous thermal events.

flowchart TD
    Detect["<b>Battery Anomaly Detected</b>"]
    Puff["<b>Physical Swelling</b><br/>Bulging chassis, lifting display, trackpad popping upward"]
    Heat["<b>Abnormal Heat</b><br/>Device feels hot to touch while idle or powered off"]
    Odor["<b>Chemical Odor</b><br/>Sweet, pungent acetone or metallic smell"]
    Active["<b>Active Smoke / Hissing</b><br/>Sparks, jet flame, or popping sounds"]

    Detect --> Puff
    Detect --> Heat
    Detect --> Odor
    Detect --> Active

    Puff --> Isolate["<b>Immediate Action:</b><br/>Unplug, power down, place in metal container with sand"]
    Heat --> Isolate
    Odor --> Evacuate["<b>Urgent Action:</b><br/>Evacuate room, isolate outdoors, prepare for thermal runaway"]
    Active --> Call911["<b>Emergency:</b><br/>Evacuate structure immediately; call fire department"]

Physical distortion and case separation¶

The most common warning sign of an aging or defective pouch cell is physical expansion. This condition is commonly called a "spicy pillow". As internal electrolytes break down through side reactions, gas builds up inside the sealed pouch:

• Laptops: The trackpad refuses to click, becomes stiff, or lifts out of the palm rest. The bottom metal or plastic chassis bows outward so the laptop rocks on a flat desk.
• Smartphones: The front display screen or rear glass panel begins separating from the frame, creating visible gaps or adhesive stretching.
• Tablets: Discoloration spots, white patches, or rainbow distortions appear on the LCD screen where internal battery pressure pushes against the display layers from behind.

Thermal and chemical symptoms¶

• Excessive heat generation: The device becomes uncomfortably hot to hold while performing basic tasks or resting in standby mode.
• Sweet chemical smell: Damaged or venting lithium cells release volatile organic solvents such as dimethyl carbonate. The vapor carries a distinctive sweet, solvent, or acetone-like smell. If you smell this near your electronics, the pouch seal has breached.
• Rapid discharge and erratic percentage jumps: The battery drains from full charge to zero in minutes, or the device shuts down abruptly at thirty percent indicated capacity.

Thermal runaway mechanics¶

Thermal runaway is an uncontrollable, self-sustaining exothermic chain reaction that occurs inside damaged lithium cells.

flowchart TD
    Cause["<b>Primary Trigger</b><br/>Puncture, overcharging, dendrite short, or heat above 60°C (140°F)"]
    Breakdown["<b>SEI Layer Breakdown</b><br/>Protective layer dissolves; internal short circuit generates localized heat"]
    Vapor["<b>Electrolyte Vaporization</b><br/>Solvents boil and create high internal pressure; pouch swells"]
    Separator["<b>Separator Collapse at 130°C to 150°C</b><br/>Anode and cathode make direct physical contact"]
    Runaway["<b>Thermal Runaway at 150°C+ (302°F+)</b><br/>Cathode releases oxygen; internal combustion generates temperatures above 1,000°C (1,832°F)"]
    Rupture["<b>Violent Venting and Fire</b><br/>Toxic jet flame, white smoke, hydrogen fluoride gas"]

    Cause --> Breakdown
    Breakdown --> Vapor
    Vapor --> Separator
    Separator --> Runaway
    Runaway --> Rupture

How the reaction unfolds¶

1. Internal breakdown: When the microscopic polymer separator between the positive and negative electrodes fails, high electrical current surges through the defect.
2. Self-heating: The short circuit generates localized heat. Once internal temperatures exceed 80°C (176°F), internal coatings decompose and release additional heat.
3. Oxygen release: At temperatures between 130°C and 150°C (266°F to 302°F), the metal oxide cathode breaks down chemically, releasing pure oxygen inside the cell.
4. Rapid combustion: The combination of oxygen, vaporized hydrocarbon electrolyte fuel, and extreme heat causes self-fueled combustion. The cell does not require ambient oxygen from the room to continue burning. Temperatures can exceed 1,000°C (1,832°F) within seconds.

Immediate actions for a swollen or damaged device¶

If your device is swollen or damaged but has not ignited, handle it with extreme care to prevent an internal short.

Extinguishing a lithium-ion battery fire¶

Extinguishing a lithium-ion electronic device fire requires cooling the cell to stop thermal runaway. Standard fire extinguishers do not extinguish the chemical reaction inside the battery cell itself.

How to react during active flames¶

1. Evacuate the area: Keep all people and pets out of the room. The dense white smoke contains toxic hydrogen fluoride, carbon monoxide, and hydrogen cyanide gas that can cause severe lung damage within breaths.
2. Call emergency services: Alert the fire department that a lithium-ion battery has caught fire.
3. Use water safely:
4. For small personal electronics (smartphones, earbuds, smartwatches), standard water from a garden hose, bucket, or fire extinguisher can be used to cool the casing and prevent fire from spreading to surrounding furniture.
5. You must apply large volumes of water continuously. A small splash of water can worsen the reaction by interacting with hot electrolyte salts. Drench the surrounding area completely to prevent structural house fires.
6. Use Class D extinguishers or dry sand:
7. For hobbyist LiPo packs or workshop environments, dry sand, Class D metal fire extinguishers, or specialized lithium fire extinguishing agents (such as Lith-Ex) are effective at smothering flames and suppressing thermal radiation.
8. Do not use standard ABC dry chemical extinguishers expecting them to halt internal cell heating. They will extinguish secondary burning plastics around the battery, but the battery cell may continue to vent and reignite.

Safe handling and quarantine protocol¶

If a battery has swollen but has not caught fire, quarantine the device safely until it can be transported to a certified recycler.

Setting up a domestic quarantine container¶

1. Locate an empty, clean metal container, such as a large steel cooking pot, metal paint can, or galvanized steel bucket.
2. Pour a 5 cm (2 inch) layer of clean dry sand, non-clumping kitty litter, or baking soda across the bottom of the container.
3. Gently place the damaged device or battery flat on top of the sand bed. Do not stack objects on top of it.
4. Cover the device with an additional 5 cm (2 inches) of dry sand.
5. Place the metal container outdoors on concrete or stone, at least 3 meters (10 feet) away from walls, wooden decks, dry leaves, and vehicles.
6. Leave the device isolated for at least 48 hours to confirm temperature stability before transport.

Air travel and airline regulations¶

Aviation safety authorities enforce strict regulations regarding lithium-ion batteries due to the catastrophic danger of cargo hold fires.

• Damaged or swollen batteries are banned from all aircraft: The Federal Aviation Administration (FAA) in the United States, the European Union Aviation Safety Agency (EASA), and the International Civil Aviation Organization (ICAO) strictly forbid boarding any flight with a visibly damaged, swollen, or recalled battery.
• Carry-on luggage only for power banks: All spare lithium-ion batteries, external power banks, and vaping devices must be packed in carry-on baggage. They are prohibited in checked luggage because cabin crew have fire containment bags and extinguishers to handle fires in the passenger cabin.
• In-flight battery emergency: If your phone or tablet becomes hot, begins smoking, or slips between passenger seat mechanisms, do not adjust your seat. Power-seat tracks easily crush and puncture smartphone batteries, triggering violent cabin fires. Alert a flight attendant immediately.

Safe recycling and hazardous waste disposal¶

Never throw a lithium-ion battery, swollen phone, or electronic device into regular household trash bins, curbside recycling bins, or incinerator chutes. Compactor blades in garbage collection trucks frequently crush batteries, sparking thousands of waste truck and recycling facility fires each year.

How to recycle safely¶

• Tape the metal contacts: Place clear packing tape or electrical tape over the exposed metal terminals of the battery to prevent short circuits during transport.
• Seal in a clear bag: Place each damaged battery in its own clear plastic bag.
• Locate a certified drop-off facility:
• In the United States and Canada, visit Call2Recycle to find authorized hazardous waste drop-off locations at hardware stores and municipal depots.
• In the United Kingdom and Europe, take batteries to local municipal recycling centres (civic amenity sites) or retailer collection points.
• Tell the staff at the drop-off counter that the battery is swollen or physically damaged so they place it in specialized fireproof vermiculite storage drums.

Frequently asked questions¶

Can I leave a swollen battery in my phone until the replacement arrives?¶

No. Once a battery begins swelling, internal physical pressure stretches the protective internal layers. Continued charging and discharging increases the risk of an internal short circuit and fire. Turn the device off and isolate it immediately.

Will putting a swollen battery in the freezer shrink it back to normal?¶

No. Freezing a damaged lithium battery does not repair chemical breakdown. Freezing temperatures cause electrolyte contraction and can introduce condensation, increasing the risk of short circuits when returned to room temperature.

Can water be poured on a burning phone?¶

Yes. Fire services recommend applying copious amounts of water to small consumer electronics fires. Water cools the battery cells, dissipates thermal energy, and halts the chain reaction in adjacent cells.

Why do power banks swell when left in cars?¶

Automotive interiors regularly reach 60°C to 70°C (140°F to 158°F) in direct sunlight. Sustained heat accelerates internal chemical decomposition, creating rapid gas buildup and permanent swelling.

Official sources and authoritative guidelines¶

• National Fire Protection Association (NFPA): Lithium-ion battery safety and hazard response guidelines.
• Federal Aviation Administration (FAA): Pack Safe regulations for passengers and commercial air operators.
• Occupational Safety and Health Administration (OSHA): Preventing fire and explosion hazards of lithium-ion batteries.
• United States Environmental Protection Agency (EPA): Used lithium-ion battery management and recycling standards.
• Call2Recycle: North American battery stewardship and safe disposal protocols.

Related guides¶

• Broken or water damaged phone
• House fire
• Electrical fire and sparks
• 3D printer thermal runaway and fires
• Emergency numbers