Why does a Lithium Ion Battery Swell?

The main structure of lithium ion battery includes three elements: positive electrode, negative electrode and electrolyte.

Swelling is common when battery ages naturally. And aging will cause short circuit which generates heat and gas. However, there are many factors will cause this kind of phenomenon. The swollen of lithium battery is mainly related to battery quality, battery using methods, environment and many other factors.

The following are some reasons which cause batteries swell from three aspects.

Let’s get start.

  • Low battery manufacturing level:

1.Poor packaging: air moisture into the cell during the production process, causing the decomposition of the electrolyte to produce gas.

2.The cell contains excessive water: in the process, once the water content of the cell exceeds the standard, the electrolyte will fail to produce gas.

3.Corrosion: lithium battery core corrosion, aluminum layer is consumed by the reaction, lose the barrier effect on water, gas.

  • Wrong battery using methods

1.Surface damage: the battery is damaged by external force, which will lead to water entering the core. In addition, the chemical properties of lithium materials are too reactive, which poses a high risk. When lithium metal is exposed to the air, it will have a fierce oxidation reaction with oxygen, and then it is easy to bulge.

2.knock: aluminum is easy to deformation, a gentle knock will be deformed. The larger the cell and the larger the air pocket, the more likely the battery will be damaged.

3.Overcharge or over-discharge: If the battery is overcharged or over-discharged and the protection plate is abnormal, the battery core will be severely swollen.

4.Leave batteries out of use for a long time

Internal short circuit: the isolation film of lithium battery shrinks, curls, damages, burrs Pierce the isolation film and other factors will cause internal disconnect. This can lead to lumps.

5.inappropriate chargers:

If we use an inferior, broken or mismatched charger, the input voltage will be incorrect. Because the voltage is too high, too low instability will make the battery lead plate active substance off, so that the battery continues to heat

  • Environment factors

High Temperature

Overheating causes the battery’s “electrolyte” to evaporate into gas. This gas is not effectively removed, resulting in increased pressure inside the battery, resulting in battery deformation and bulge. So on a hot summer day, the “electrolyte” is more likely to evaporate and the battery is more likely to bulge.

How to Judge if a Lithium Ion Battery Swells or not?

  • Look

For battery itself

1.directly inspect and check your battery whether all surfaces are flat or not.

For equipped devices

1.If shape of device changes
2.If device is easy to open

  • Sniff

When you sniff strange smell from your device, electrolyte leaks. Stop using it at once.

How to Proposal Swollen Lithium Battery?

No matter if your device can work or not, the sooner you handle it, the better. If your battery is replaceable, remove it.

  • Before you remove
please notice following matters:
1.Let swollen battery discharge by its own. It is safer to remove when the battery is out of power.
2.Do not charge your swollen battery
3.Be in a suitable environment. Open air environment is the optimistic choice.
4.Clear flammable materials.
5.Equip yourself with protecting clothes.

  • During removing
it is a easy process, but you still need to attend

1.Use plastic tools
2.Do not use sharp tool

  • After removing:
1.Keep away from children
2.Put it into a fireproof container
3.Take it to recycle center as soon as possible

If you are afraid, you can also let professional people to handle it. It is more safer.

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Lithium Battery Design Design Ebook Download(2M, 20 pages, PDF)

How to decrease the possibility of swelling for Li-ion battery?

1.Choose high-quality battery.

2.Charging battery with matched charger and in right way. Do not over charge or over discharge.

Can you continue using swelling lithium ion batteries?

No, it is best for you to continue using it. Continue using it fasten swelling degree.

Firstly, for your safety, the swollen battery has a risk to explode or fire when it expands to its limit or in high temperature as the same as a balloon.

Secondly, for bad performance. When swell occurs, it will decrease battery performance. Discharging time shortens which will influence our daily usage.

So we’d better change a new one.
Tips: if your battery is swollen, please put them away from fire

Will a swollen lithium ion battery be healed by itself?

Nope. Gas in swollen battery has nowhere to release, and gas will not join chemical reaction about charging or discharging, so it will not shrink by itself

Can you put a swollen lithium ion battery in the freezer?

No, you can’t. It’s useless to put a swollen battery in your freezer and it will even pollute your delicious food. Generally speaking, when battery swells, its capacity will losses nearly 50% which is depends on the swelling degree.

Can you fix a swollen lithium battery?

No, you just give up this idea. The only thing you need do is replace the swollen battery if your battery is replaceable. Or you only have to replace your device.

What will Happen If You Pierced a Swollen Li-ion Battery?

Some people believe that swollen batteries will be fixed if they release inner gas. It is a fake opinion. There is a potential risk of fire or explosion. Do not easily try it.

If you do it without a gas mask. Hold up your breath. Do not take in harmful gas. And you’d better run away.

Will Swelling Lithium Batteries Damage Your Devices?

Of course yes. The structure of your device is carefully designed, the space of battery is limited. Once the battery swells, it will definitely forces other components in your device. That’s the reason why we can check your battery whether swells or not according to your device’s shape.

Can You Throw Swollen Lithium Battery into Trash Can?

Of course not. When you have removed your swollen battery, you’d better take it to recycling center to avoid fire or explosion accident. And this is a good way to recycle lithium and other metal materials which can protect sources and environment.

In all, when you meet swollen batteries, do not afraid about it. You just follow instructions I have mentioned above, you can keep yourself safe.

Is a Swollen Lithium Battery Dangerous?

Yes. It has risk of polluting surrounding air, fire and even explosion.But if you carefully handle swollen batteries and not pierce them, they are not worth concerning.

Are Swollen Lithium Batteries Normal?

Battery swelling is common when battery ages naturally. It is a signal that its cycle life came to an end. What we can do is understanding causes and trying to avoid this phenomenon as much as possible.

Safety Instructions for Lithium Batteries

Warnings for Handling

Improper handling of the battery could lead to distortion,overheating, explosion, or fire, causing bodily injury or equipment trouble. Please observe the following instructions to prevent accidents.

  • Avoid Swallow.

Always keep the battery away from infants and young children to prevent it from being swallowed. If swallowed, consult a physician immediately.

  • Do not  reverse the positive and negative terminals when mounting

Improper mounting of the battery could lead to equipment trouble or short-circuiting. This could cause distortion, leakage, overheating, explosion, or fire.

  • Avoid short-circuit.

Do not allow the positive and negative terminals to short-circuit. Never carry or store the battery with metal objects such as an ecklace or a hairpin. Do not take multiple batteries out of the package and pile or mix them when storing. Please be careful when installing the battery not to short-circuit it with metal portions of the equipment. Otherwise, this could lead to distortion, leakage, overheating, explosion, or fire.

  • Do not heat lithium battery

Heating the battery to more than 100 deg. C could increase the internal pressure, causing distortion, leakage, overheating, explosion, or fire.

  • Do not expose to open flames

Exposing to flames could cause the lithium metal to melt, causing the battery to catch on fire and explode.

  • Avoid disassemble the battery.

Do not disassemble the battery, because the separator or gasket could be damaged, leading to distortion, leakage, overheating, explosion, or fire.

  • Do not weld the terminals or weld a wire to the body of the  battery directly.

The heat of welding or soldering could cause the lithium to melt, or cause damage to the insulating material in the battery, leading to possible distortion, leakage, overheating, explosion, or fire. When soldering the battery directly to equipment, solder only the tabs or leads. Even then, the temperature of the soldering iron must be below 350 deg. C and the soldering time less than 5 seconds. Do not use a soldering bath, because the circuit board with battery attached could stop moving or the battery could drop into the bath. Moreover do not use excessive solder, because the solder could flow to unwanted portions of the board, leading to a short-circuit or charging of the battery.

  • Avoid liquid leaking from the battery to get in your eyes or mouth.

Because this liquid could cause serious damage, if it does come in contact with your eyes, flush them immediately with plenty of water and consult a physician. Likewise, if the liquid gets in your mouth, rinse immediately with plenty of water and consult a physician.

  • Keep leaking batteries away from fire.

If leakage is suspected or you detect a strong odor, keep the battery away from fire, because the leaked liquid could catch on fire.

  • Do not touch the battery electrodes

Do not allow the battery electrodes to come in contact with your skin or fingers. Otherwise, the moisture from your skin could cause a discharge of the battery, which could produce certain chemical substances causing you to receive a chemical burns.

Warnings — Circuit Design


  • Never set the charge voltage above 3.3V.

Charging at a higher voltage could cause the generation of gas, internal short-circuiting, or other malfunctions, leading to distortion, leakage, overheating, explosion, or fire. For details, see the recommended circuits below.


  • Always charge at the nominal currents shown below.

Large surges of current could degrade the battery’s characteristics, leading to distortion, leakage, overheating, explosion, or fire. To avoid excessive current at the initiation of charging, make sure to attach a protective resistor for current control. See the recommended circuits below.


  • Recommended circuits

Please refer to the representative basic circuits shown below. If you have any questions about circuit design, please feel free to contact Maxell.

(How to select a protective resistor for the current control)

The maximum charge current flows in the battery when charged at an end voltage of 2V. Therefore, the value of the resistor is calculated using this equation:

(R) >= ((Output Voltage of Voltage Regulator) – 2) / (Nominal ChargeCurrent)

For example, the S-812C series, which has a maximum input voltage of 18V, or the S-817 series with a maximum input voltage of 10V (Seiko Instruments Inc.) can be used as a voltage regulator.

Note 1: If the main power source voltage is stable, the charge voltage can be allotted from main power source divided by the combination of resistors.

Note 2: Because the battery height must be changed by charge and discharge cycle, place a minimum of 1mm space between the battery and device or chassis.

  • Never over-discharge the battery

If the battery is over-discharged to below the specified voltage(2.0 V), it may not be rechargeable.

Warnings — Disposal

The battery may be regulated by national or local regulation. Please follow the instructions of proper regulation. As electric capacity is left in a discarded battery and it comes into contact with other metals, it could lead to distortion, leakage, overheating, or explosion, so make sure to cover the (+) and (–) terminals with friction tape or some other insulator before disposal.

Caution — Handling/Storage

  • Never expose the battery to ultrasonic sound

Exposing the battery to ultrasonic sound may cause short-circuiting because the inside material is broken into pieces, leading to distortion, leakage, overheating, explosion, or fire.

  • Never subject the battery to severe shock.

Dropping, throwing or stomping on the battery may cause distortion, leakage, overheating, explosion, or fire.

  • Use the correct battery suitable for the equipment.

The battery may not be suitable for the specific equipment due to the using conditions or type of equipment. Please select the suitable battery according to the handling instructions of the equipment.

  • Never use or leave the battery in a hot place such as under the  direct rays of the sun or in a car in hot weather

If you do, this may cause distortion, leakage, overheating, explosion, or fire.

  • Never allow the battery to come in contact with water.

If it does, this may cause the battery to rust or lead to distortion, leakage, overheating, explosion, or fire.

  • Never store the battery in a hot and highly humid environment.

Doing so may cause the performance of the battery to deteriorate. In certain environments, this may lead to distortion, leakage, overheating, explosion, or fire.

Want More Details: Download our battery design ebook.

Lithium Battery Design Design Ebook Download(2M, 20 pages, PDF)