If you’ve ever noticed a bulging or swollen lithium battery inside your device, it’s a serious warning sign that should never be ignored.
Swelling indicates gas buildup inside the battery, which can lead to leakage, overheating, or even fire if handled incorrectly.
In this article, Jiangmen Hongli Energy Co., Ltd., a trusted manufacturer of 3V primary lithium batteries, explains what causes lithium batteries to swell, how to deal with them safely, and how to prevent it from happening again.
1. What Causes a Lithium Battery to Swell?
Lithium battery swelling occurs when chemical reactions inside the cell become unstable. This instability causes gas generation and pressure buildup, making the battery pouch or casing expand.
The Main Causes Include:
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Overcharging
When a rechargeable lithium battery (Li-ion or Li-Po) is charged beyond its voltage limit (4.2V), the electrolyte breaks down, releasing gases like carbon dioxide and oxygen. -
Deep Discharge
Discharging a lithium battery below 2.5V can cause copper in the electrodes to dissolve, leading to internal short circuits. -
High Temperature
Exposure to excessive heat (>60°C) accelerates chemical decomposition inside the cell. -
Aging or Long-Term Use
As batteries age, the internal separator weakens and gases accumulate, slowly causing swelling. -
Poor Manufacturing or Damage
Substandard materials or physical impact can cause microscopic internal shorts, triggering heat and gas formation.
? Note:
Hongli Energy’s 3V primary lithium batteries (Li/MnO₂) are non-rechargeable and hermetically sealed in stainless steel, so they do not swell under normal conditions — a key advantage over rechargeable lithium-ion systems.
2. Is a Swollen Lithium Battery Dangerous?
Yes — very dangerous.
A swollen lithium battery poses risks of fire, leakage, chemical burns, and explosion if punctured or charged. The swelling indicates internal damage that cannot be repaired.
Why It’s Hazardous:
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The internal pressure may rupture the casing.
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Flammable gases may escape and ignite if exposed to air.
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The electrolyte is corrosive and toxic if it leaks.
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Overheated batteries can damage nearby electronics or cause smoke.
⚠️ Never try to flatten, puncture, or squeeze a swollen battery.
Doing so may cause a short circuit or fire instantly.
3. Signs of a Swollen Battery
You may not always see obvious swelling, but these clues indicate something is wrong:
| Symptom | Possible Cause |
|---|---|
| Device case bulging | Battery expanding inside |
| Battery feels soft or bloated | Gas buildup |
| Device runs hot or shuts down | Internal short circuit |
| Strange smell or hissing | Electrolyte leakage |
| Charger light blinking abnormally | Battery failure detected |
If any of these occur, stop using the device immediately and follow safe disposal procedures.
4. What To Do With a Swollen Lithium Battery
Step 1: Turn Off the Device
Immediately power off the device and unplug it from the charger.
Do not continue using it even if it still functions.
Step 2: Do Not Puncture or Compress
Avoid touching the battery with sharp objects or trying to flatten it.
The internal gases are flammable and can ignite upon exposure to oxygen.
Step 3: Remove the Battery Carefully (if possible)
If the battery is user-removable, wear insulated gloves and remove it gently without bending or pressing it.
If not, take the device to a certified technician — do not attempt to open sealed devices yourself.
Step 4: Place It in a Fireproof Container
Put the swollen battery in a non-conductive, fire-resistant surface or container, such as:
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A metal box lined with sand
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A ceramic or glass jar (not plastic)
Step 5: Take It to a Recycling or Hazardous Waste Center
Do not throw the battery in household trash or recycling bins.
Instead, bring it to:
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Local e-waste recycling centers
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Battery drop-off points
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Authorized hazardous waste facilities
These facilities have the equipment to neutralize and recycle lithium batteries safely.
5. What NOT To Do with a Swollen Battery
❌ Do not try to charge or discharge it.
❌ Do not puncture, crush, or burn it.
❌ Do not store near heat sources or in sunlight.
❌ Do not mix it with normal waste.
❌ Do not reuse or ship it internationally — damaged batteries are prohibited under UN regulations.
6. How To Prevent Lithium Battery Swelling
Proper care and usage can significantly reduce the chance of swelling.
6.1 Use the Right Charger
Always charge batteries with a compatible, certified charger.
Avoid overcharging by unplugging once full.
6.2 Avoid Extreme Heat
Keep devices out of hot cars, direct sunlight, or enclosed places with poor ventilation.
6.3 Store at 40–60% Charge (Rechargeables Only)
If storing lithium-ion batteries long-term, keep them partially charged and at cool temperatures.
6.4 Use Quality Batteries
Choose products from reputable manufacturers like Hongli Energy, whose batteries undergo strict quality and safety testing.
6.5 Replace Aging Batteries Promptly
If a device’s runtime drops sharply or gets unusually warm, replace the battery before it becomes unstable.
7. Why Hongli Energy Batteries Are Safe and Stable
At Jiangmen Hongli Energy Co., Ltd., safety is built into every step of design and production.
Our 3V primary lithium batteries (Li/MnO₂ chemistry) are engineered for stability, leak-proof sealing, and long-term reliability.
Key Safety Features:
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Hermetically sealed stainless-steel housing
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PTC protection to prevent overcurrent and short-circuit
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Pressure relief vent for controlled gas release in rare cases
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High-purity materials ensuring consistent chemical reactions
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Operating temperature: −40°C to +70°C
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Shelf life: up to 10 years with <1% annual self-discharge
Every batch is tested according to UN38.3, CE, RoHS, and ISO9001 standards — ensuring safety during production, usage, and international transport.
8. Quick Summary: What To Do with a Swollen Lithium Battery
| Step | Action | Purpose |
|---|---|---|
| 1 | Power off device immediately | Prevent further damage |
| 2 | Do not puncture or crush | Avoid ignition or leakage |
| 3 | Remove safely if possible | Reduce internal pressure |
| 4 | Store in fireproof container | Isolate from flammable materials |
| 5 | Take to recycling center | Ensure proper disposal |
Following these steps ensures personal and environmental safety.
9. Hongli Energy — Committed to Battery Safety
As a National High-Tech Enterprise established in 2015, Hongli Energy produces more than 40 million high-performance lithium batteries annually, serving global partners in industrial, security, and metering applications.
We design batteries that not only deliver stable energy output but also prioritize user safety — reducing risks like swelling, leakage, or short-circuiting.
To learn more about our certified 3V lithium batteries or discuss OEM/ODM cooperation, visit www.honglienergy.com.