What causes lithium batteries to swell?

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What causes lithium batteries to swell?

What causes lithium batteries to swell? Jan. 04, 2024

What causes lithium batteries to swell?


Lithium-ion polymer batteries are widely used due to their long life and high capacity. However, there are some issues that can arise, such as swelling, unsatisfactory safety performance, and accelerated cycle attenuation. This article will primarily focus on battery swelling and its causes, which can be divided into two categories: the first is a result of a change in thickness of the electrode, and the other is a result of the gas produced by the oxidation and decomposition of electrolytes.

The change in thickness of the electrode pole piece

When a lithium battery is used, the thickness of the electrode pole pieces, especially the graphite negative electrodes, will change to a certain extent. Lithium batteries are prone to swelling after high-temperature storage and circulation, and the thickness growth rate is about 6% to 20%. Of this, the expansion rate of the positive electrode is only 4%, the negative electrode’s is more than 20%. The fundamental reason for the increase in the thickness of the lithium battery pole piece is due to the nature of graphite. The negative electrode graphite forms LiCx (LiC24, LiC12, LiC6, etc.) when lithium is inserted, and the lattice spacing changes, resulting in microscopic internal stress and an expansion of the negative electrode.


The figure is the schematic diagram of the structure change of the graphite anode plate in the process of placement, charge, and discharge.(Source: Internet)

The expansion of graphite negative electrodes is mainly caused by irreversible expansion after lithium insertion. This part of the expansion is mainly related to the particle size, the adhesive, and the structure of the pole piece. The expansion of the negative electrode causes the core to deform, which in turn causes the following: a cavity between the electrode and the diaphragm, micro-cracks in the negative electrode particles, breaking and reorganizing of the solid electrolyte interface (SEI) membrane, the consummation of electrolytes, and deterioration of the cycle performance. There are many factors that affect the thickness of the negative pole piece although the properties of the adhesive and the structural parameters of the pole piece are the two most important reasons. The commonly used bonding agent for graphite negative electrodes is SBR. Different bonding agents have different elastic modulus and mechanical strength and have different effects on the thickness of the pole piece. The rolling force after the pole piece is coated also affects the thickness of the negative pole piece in battery use. When the amount of SBR added is inconsistent, the pressure on the pole piece during rolling will be different. Different pressures will cause a certain difference in the residual stress generated by the pole piece. The higher the pressure, the greater the residual stress, which leads to physical storage expansion, a full electric state, and an increase in the expansion rate of the empty electric state. The expansion of the anode leads to the deformation of the coil core, which affects the lithium intercalation degree and Li + diffusion rate of the negative electrode, thus seriously affecting the cycle performance of the battery.

Bloating caused by lithium battery gas production

The gas produced in the battery is another important cause of battery swelling. Dependent on whether the battery is in a normal temperature cycle, high-temperature cycle, or high-temperature shelving, it will produce different degrees of swelling and gas production. According to the current research results, cell bloating is essentially caused by the decomposition of electrolytes. There are two cases of electrolyte decomposition: one is that there are impurities in the electrolyte, such as moisture and metal impurities, which cause the electrolyte to decompose and produce gas. The other is that the electrochemical window of the electrolyte is too low, which causes decomposition during the charging process. After a lithium battery is assembled, a small amount of gas is generated during the pre-formation process. These gases are inevitable and are also the source of irreversible capacity loss of the battery. During the first charging and discharging process, the electrons from the external circuit to the negative electrode react with the electrolyte on the surface of the negative electrode to generate the gas. During this process, the SEI is formed on the surface of the graphite negative electrode. As the thickness of the SEI increases, electrons cannot penetrate and inhibit the continuous oxidation and decomposition of the electrolyte. When a battery is used, the internal gas production gradually increases due to the presence of impurities in the electrolyte or excessive moisture in the battery. These impurities in the electrolytes need to be carefully removed. Inadequate moisture control may be caused by the electrolyte itself, improper battery packaging, moisture, or damage to the corners. Any overcharge and over-discharge, abuse, and internal short-circuiting will also accelerate the gas production rate of the battery and cause battery failure. In different systems, the degree of battery swelling is different. For instance, in the graphite anode system battery, the main causes of gas swelling are the SEI film formation, excessive moisture in the cell, abnormal chemical conversion process, poor packaging, etc. In the lithium titanate anode system, battery swelling is more serious. In addition to the impurities and moisture in the electrolyte, lithium titanate cannot form an SEI film on its surface like a graphite-anode system battery to inhibit its reaction to the electrolyte. If you are interested in good quality battery products, please don't hesitate to contact us at any time! Email: info@grepow.comGrepow Website: https://www.grepow.com/

What causes the lithium battery swelling – Maxworld Power

The first reason that the change in the thickness of the electrode plate. When using a lithium-ion battery, the thickness of the electrode plates, especially the graphite negative electrodes, will change to some extent. Lithium-ion batteries are easy to expand after being stored and circulated at high temperatures, with a thickness growth rate of about 6% to 20%. Among them, the expansion rate of the positive electrode is only 4%, and the expansion rate of the negative electrode exceeds 20%. The fundamental reason for the increase in the thickness of the electrode plate is the nature of graphite. The nature of graphite is the fundamental reason for the increase in the thickness of the lithium polymer battery pole piece. It is the irreversible expansion after lithium intercalation that causes the graphite anode to expand. The particle size, the adhesive, and the pole piece structure are the main reasons for this part of the expansion. The expansion of the negative electrode causes deformation of the core. Further, it leads to the following situations: a cavity between the electrode and the separator, micro-cracks in the negative electrode particles, the rupture, and recombination of the SEI film, the perfection of electrolytes, and deterioration of the cycle performance. Sometimes, a lithium car battery can also play an important role.

Will a swollen battery explore - helpful guide to deal with battery swelling




Batteries can indeed swell like a balloon after using them for some time. Swollen batteries are extremely dangerous and need to be handled with a lot of care to avoid fires and explosions that may occur under certain circumstances. When your battery swells, you’ll need to proceed with a lot of caution when you decide to remove the swollen battery and fix a new one by yourself. As with battery corrosion, leaving the swollen batteries in your device may also poses risks. This article is designed to help you understand:


What causes a lithium rechargeable battery to swell.


How to handle a swollen battery safely.


How to prevent your Li-ion battery from swelling.

Let’s get right to it!




1.What is a swollen battery?

A swollen battery refers to a battery that bulges and swells during use. First things first - it would be best to understand what causes a battery to swell. Your Li-ion battery can swell because of having too much current flowing in them causing a buildup in gasses and heat. as a result of overcharging, deep discharging, or even when your Li-ion battery is damaged. It would be best if you’d acquire your Li-ion battery from a trusted battery store - your battery could swell as a result of defects from the manufacturer. TYCORUN ENERGY is your optimum selection, our products have been tested and qualified, and the quality is more guaranteed.


2.What happens when a battery swells?What causes a swollen battery to explode?

As you've read earlier in this article, a swollen battery is caused by a buildup of gasses and heat due to excessive flow of current. As such, swollen batteries may explode and cause a fire. It would be best if you’d stop using swollen batteries - doing so might save your life as well as your property. Swollen batteries are dangerous. You’ll need to be highly cautious, should you decide to replace the battery by yourself. 

Swollen batteries may explode even if they are not plugged in power. When left in devices, they can explode on your hand when holding your device, which may lead to serious injuries that may lead to death. Most Li-ion batteries have a highly flammable liquid electrolyte except for solid-state lithium-ion battery. When your battery starts leaking the electrolyte, it could explode and cause a fire. That’s what causes swollen batteries to explode. Now, you may be thinking to yourself: “How can I identify a swollen battery?” Here’s how.

3.How to identify a swollen battery?

Identifying battery swelling is quite straightforward - the battery increases in size, similar to what a balloon does when air is blown into it. Consider this example: To find out whether your smartphone has a swollen battery, you’ll begin noticing any, if not all of the following signs:


Your phone’s touchpad lifts.


When you place your phone on an even surface, for example, a table or a countertop, the phone rocks.

Your phone’s enclosure splits.

4.Is it safe to use a slightly swollen battery?

No, using a swollen battery, regardless of whether it is slightly or greatly swollen is dangerous. Once you notice that your Li-ion battery is swollen, consider reaching out to battery experts to help you replace them. Remember, having swollen batteries inside your devices is also risky as they may explode and cause a fire.

5.How best to deal with a swollen battery?

After noticing that your battery is swollen, consider removing it carefully. Should you feel any difficulty or the battery is simply not removable, please stop and reach out to an authorized and experienced battery repairer. If you are successful in removing it, consider placing it in a strong container in a cool place away from direct sunlight and other metallic parts.

6.How to safely remove a swollen battery from your devices?

When removing a swollen battery from your device, do not attempt to puncture the batter hoping to release the pressure buildup inside it. Instead, be firm and gentle with it - should you feel any form of resistance, stop the removal process immediately.

7.Can a swollen battery be fixed?

No, swollen batteries cannot be fixed. The best you can do is to remove and replace the swollen battery with a new one from a reputable Li-ion battery manufacturer. Now, since swollen batteries cannot be fixed, it, therefore, means that anyone who tries to sell you fixed Li-ion batteries is messing with you.

8.How to prevent your battery from swelling?

Here’s what you can do to prevent your batteries from swelling:


Avoid leaving your Li-ion battery plugged in all the time(especially on laptops and smartphones).


Always use the correct charger. If you mistakenly lose your original charger, consider acquiring one from your manufacturer or an approved aftermarket charger by your device's manufacturer.


If you notice that your battery is no longer fit for use, consider replacing the battery. Doing so will prevent the battery from swelling.


It would be best if you’d store your batteries in cool dry places, away from other metallic parts.High-quality BMS can also monitor the status of the battery in real time, prevent the battery from overcharging and overdischarging, and prevent the battery from swelling.  The TYCORUN





are all equipped with premium BMS to avoid the hidden trouble of battery swelling.

9.Can you fly with a swollen battery?

No, it would be best to avoid carrying a swollen battery on an airplane. Why? Because swollen batteries may explode and cause your airplane to crash, therefore, destroying the lives of many as well as property.

10.Final thoughts

Finding swollen batteries is not common. You can consider a battery swollen if it is almost similar to an air-filled balloon. Swollen batteries usually have a buildup of gasses and heat caused by the passing of excessive current inside the battery. Common swollen batteries cause are normal battery damage, a faulty battery from the battery store, overcharging, and deep discharging among others. It is dangerous to use swollen batteries, regardless of whether the swell is small or great.

When dealing with swollen batteries, it would be best if you'd remove it from your device to prevent an possible explosion. Remember, leaving it inside the device does not help, and it would be best if you'd remove it. When removing swollen batteries from your device, it would be best if you did it slowly. Should you feel any sort of resistance, discontinue the whole process and take the battery to an expert to help you remove it.

Unfortunately, swollen batteries cannot be fixed. Do not attempt to pierce swollen batteries to relieve them from pressure buildup. Also, avoid boarding airplanes with swollen batteries as they could explode mid-air and may cause a fatal accident. Swollen batteries are dangerous and their use must be discontinued immediately to prevent battery explosions which might lead to serious injuries and loss of property. However, you can avoid these risks by choosing a professional and trustworthy battery store, the TYCORUN best lithium batteries is undoubtedly your optimal choice.

Related article: lithium battery recycling, used lithium batteries

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