Lithium-ion batteries are widely used in a wide range of devices. The reason is that these batteries offer high energy density despite their compact size. Despite many benefits, these batteries can swell, which affects their performance. If a battery swells, it may never perform as well as before. But why do lithium-ion batteries swell?
Multiple factors can cause lithium batteries to swell. The main reason is gas trapped inside the battery cell. These gases make the pouch (cover) expand, making the battery look bulged out. In this article, I will cover everything about lithium batteries swelling and the main causes. So, let’s get started!
Overview of Lithium-ion Batteries
Lithium-ion batteries are rechargeable, reliable, and used in various devices. They are compact, lightweight, and provide high energy density. Due to this, these batteries are widely used in compact devices. These batteries work by moving lithium ions between the anode and cathode. What makes lithium-ion batteries stand out is their durability and longevity.
In the past, lead-acid batteries were common. However, those batteries were inefficient and had safety issues. That’s where lithium-ion batteries come in. These batteries offer excellent energy density and are very safe. They work by moving lithium ions.
The battery has two electrodes: the cathode and anode. A physical barrier called a separator keeps these electrodes separated. When the battery charges, lithium moves through the electrolyte and deposits on the anode. When the battery is used, these stored lithium ions move toward the cathode.
This ion movement creates electrical energy that powers different devices. As I said above, lithium-ion batteries are very safe. However, as these batteries age, they can pose some issues. Their performance can be affected as they age. They become sensitive to overheating and can swell, especially if not used with care. However, new lithium-ion batteries are very safe and don’t overheat.
What Is Lithium-Ion Battery Swelling?
Lithium-ion battery swelling means the battery is abnormally sized. Over time, as the battery ages, it can start to bulge. As a result, the battery becomes larger than normal. This bulging is so prominent that you can notice it with the naked eye. Swollen lithium-ion batteries are not safe to use because they can leak and cause a fire.
Wondering what causes lithium-ion batteries to swell? Several factors can contribute to battery swelling. The most common causes are ageing, overheating, and overcharging. As discussed above, a chemical reaction occurs that produces energy.
Sometimes, this chemical reaction gets intense due to overheating and overcharging. As a result, the reaction damages internal components and affects the electrolyte as well. This produces gas inside the battery’s container or pouch. This gas makes the batteries swell and bulge, which affects overall battery performance.
Is it wise to use a swollen battery? Absolutely not!
Swollen lithium-ion batteries mean the internal components are damaged. Using such a battery can cause it to leak and catch fire, which is a safety risk. Additionally, bulged lithium-ion batteries don’t perform well. You won’t get optimal energy density, power and longevity from such batteries. So, it is best not to use swollen lithium-ion batteries.
Why Do Lithium-Ion Batteries Swell? Major Causes
As mentioned above, several factors contribute to lithium-ion battery swelling. In the section below, I will discuss some key reasons for battery swelling:
1- Electrolyte Breakdown
Electrolyte is one of the most important parts of lithium-ion batteries. It is a material inside a battery that allows lithium ions to move. Typically, this electrolyte remains stable and does not deteriorate. But under high temperatures, this electrolyte can degrade and break down. This breakdown produces different gases inside the battery. These gases can include carbon dioxide, carbon monoxide, and others. These gases build pressure inside and can cause the battery to bulge and swell.
2- Overcharging & Overheating
Both overcharging and overheating can contribute to lithium-ion battery swelling. How? When a battery is overcharged, it is exposed to very high voltage. This voltage affects the internal components. These components face stress, break down, and produce gases that make the battery swell. Overheating also damages the internal components. Therefore, you should also protect your lithium-ion battery from overcharging and heating.
3- Battery Ageing
You’ll see almost all battery types swell when they are too old or aged. Why? Batteries swell because they undergo charging and discharging. This process stresses their internal parts. As a result, internal parts become weak and eventually break down. This breakdown produces gas, which causes swelling. Ageing causes swelling not only in lithium-ion batteries but in all types. Unfortunately, there is no way to prevent swelling issues caused by ageing. All types age, eventually deteriorate, and swell.
4- Deep Discharge & Overcharge
Most of us use batteries without any care, right? We use them till they are dead and charge them beyond their limit. This deep charging and discharging harms the battery. Fully charging batteries stresses their components. This causes batteries to deteriorate and swell. Use the battery when it’s at 20%. When charging, don’t keep the battery charging even after it reaches 100%. Ideally, charge the battery to 85 to 90% instead of 100 to avoid overcharging issues.
5- Lithium Plating & Physical Damage
Lithium plating may not be the most common cause, but it can happen. This happens when lithium builds up on the anode and remains there. Over time, this buildup can become significant and affect battery performance. This is more common when the battery is fully drained and then charged. Because of lithium plating, internal components are stressed, which results in swelling. Physical damage from bending, dropping, or crushing can also cause lithium batteries to swell. Remember, a sudden impact can also damage the separator.
Prevention of Lithium-Ion Battery Swelling
Undoubtedly, lithium-ion batteries swell – there is no denying it. However, you can prevent this swelling if you take good care of your batteries. In the section below, I will discuss some prevention methods that can help you avoid swelling issues:
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Avoid Excessive Heat
First things first – you should never keep the battery at high temperatures. Also, when using or charging, make sure the battery doesn’t overheat. Overheating is one of the main reasons lithium-ion batteries swell. Overheating is common, but you can prevent it by following the right tips.
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Use the Correct Charger
Different chargers are available on the market. However, not all of them are good quality. Use the charger recommended by the manufacturer. Some chargers can charge the battery very quickly. Avoid these chargers, as fast charging can overheat the battery.
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Extreme Charging Conditions
Lithium-ion batteries should not be placed in harsh conditions. Both very high and very low temperatures harm battery health. Low temperatures freeze the internal components and electrolyte. This can cause these components to break down, leading to swelling.
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Avoid Deep Discharging
Deep discharging can be very stressful for batteries, regardless of type. When the entire stored energy is consumed, the battery’s components are exposed to stress. This stress affects the electrolyte, producing gas which causes pressure inside. This pressure can make the battery swell.
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Place Battery in Well-Ventilated Areas
First, when storing, never keep the battery 100% charged. Instead, store it at around 70 to 80% charge. Also, keep it in a ventilated area so it doesn’t overheat. Ventilation (exposure to air) keeps the temperature low. This protects the battery from overheating, especially in hot summer.
Why Are Pouch Batteries More Obviously Swollen?
Yes – pouch batteries show visible swelling. When they have issues, they look bulged out, which you can see and feel. Why? Because these pouches use a very flexible covering. Internal pressure makes the flexible pouch bulge out. This can make the swelling on the pouch battery more prominent.
It is worth noting that different lithium-based batteries are available on the market. Some batteries come in a pouch style. Their outer covering is very flexible. When internal components (over time) break down, this produces gas. This gas puts pressure on the flexible covering, making it bulge.
On the other hand, cylindrical or prismatic lithium-ion batteries have a hard outer casing. This casing resists internal pressure. So, even as they degrade, these batteries do not swell. Different batteries show different swelling or bulging patterns. However, this swelling is bad for all types of batteries. Swollen batteries can even catch fire if they leak and are used aggressively. I don’t recommend using swollen lithium-ion batteries.
Conclusion
Let’s conclude: lithium-ion batteries are safe – that’s the major reason behind their popularity. However, when these batteries age, they can develop several issues. Among these, swelling is common. The main reasons lithium-ion batteries swell are overheating, overcharging, and deep discharging.
When swollen, these batteries do not perform efficiently. In fact, swollen batteries can even leak and catch fire if you keep using them. This also poses a serious safety risk. In this article, I discuss everything about swelling in lithium-ion batteries. You’ll learn the key causes and prevention methods to help keep your battery in good condition.