Common Causes of Lithium Battery Explosion and Avoidance Measures

You might have noticed that there are several fire or explosion accidents caused by lithium battery. Are you curious about the reasons? Will lithium battery really cause explosion?  Yes, lithium battery will explode in certain circumstances. Thus you should take care of it while using.

You will get efficient and thoughtful service from HUIYAO.

Almost most of the safety accidents caused by lithium batteries are caused by short circuits.

1. Avoid short circuit and overcharge

Almost most safety accidents caused by lithium batteries are caused by short circuits.

We know that when the positive and negative electrodes of the battery are connected to each other in an abnormal path with very small resistance, which is what we often call a short circuit.

A very large current and heat will be generated inside the battery.

The heat generated and the release of too strong electrical energy will not only cause serious damage to the battery life, but also for lithium batteries made of airtight packaging.

A certain amount of pressure will be generated inside the battery, which will cause a sudden increase in the internal pressure of the battery. In addition, because the chemical properties of lithium ions are very active, the shell will eventually burst and burn.

Due to the chemical properties of lithium-ion batteries, when we overcharge the battery, the negative electrode of the lithium battery cannot be embedded with more lithium ions. And the lithium ions precipitate with lithium metal on the surface of the negative electrode, causing the phenomenon of dendrite lithium. When the dendrite lithium grows to a certain extent, it will pierce the diaphragm, causing a short circuit inside the battery. And also the dentrite lithium will damage the isolation film. Eventually, an internal short circuit will also occur, causing a safety accident.

Therefore, when we use lithium batteries in our daily lives, we should try our best to avoid short circuits or overcharges. However, for most current digital products, the internal charging circuit will be equipped with corresponding protection IC to avoid overcharging of lithium batteries. When the protection circuit detects that the lithium battery has reached full power, it will automatically cut off the charging circuit.

However, it is still not recommended to connect mobile phones or other devices to the charger in the powered state for a long time.

After all, no one wants to use their mobile phones or other devices or even personal safety to bet on a small charging protection chip.

2. Avoid Piercing Lithium Battery

Compared with short-circuiting and overcharging, piercing lithium batteries is also a very unwise approach. If the lithium battery is pierced by any hard object, the lithium ions inside it will directly react chemically with the oxygen in the air, and it will also burn violently.

When our lithium battery inevitably is swollen, it is very dangerour to pirece the battery. More details:https://www.dnkpower.com/lithium-battery-swelling/

For lithium batteries themselves or other electronic products that contain lithium batteries inside, we usually see eye-catching trash can signs. If lithium batteries are discarded at will, they will not only cause environmental pollution, but also be more prone to fire and other situations during garbage disposal.

3. Avoid High Temperature and Fire Roasting.

High temperature or fire burning can also cause the explosion and combustion of lithium batteries. Especially in the hot summer or long-term exposure to the sun in the car, the ambient temperature of the lithium battery will be higher than its normal storage temperature.

Therefore, when we use equipments with lithium-ion batteries, we should try to avoid long-term using in environments with high temperatures.

Although lithium batteries explode and burn for a relatively long time when they are directly roasted by fire, there will still be a sudden increase in their internal pressure, which is what we often call swelling.

When our mobile batteries or other lithium-ion batteries is swelling, the power supply should be cut off immediately and stopped to prevent further internal pressure from increasing, and replace the batteries with new ones.

Want More Details: Download our battery design ebook.

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

Summarize some situations of explosion in the production and use of lithium batteries&#;

1&#; Overcharge explosion

When the charging voltage to be greater than 5V which is caused by that the protection circuit or the detection cabinet are out of control, the electrolytr will decompose. Violent reactions occur inside the battery. The battery will explode because of the increasing pressure.

2.Over-current explosion(Rarely Occurs)
The protection circuit or the detection cabinet are out of control, causing the charging current to be too large, causing the lithium ions to be too late to be embedded, and the lithium metal is formed on the surface of the electrode sheet, penetrating the diaphragm, and the positive and negative electrodes are directly shorted, causing an explosion (rarely occurs).

If the protection circuit or the detection cabinet are out of control, lithium ions will be too late to embedded in cathode. And the lithium ions will form lithium on the surface of the electrode sheet. Then the metal will pierce the diaphragm. Short circuit occurs, explode.

3&#; Explosion when ultrasonic welding plastic shell

When ultrasonic welding the plastic shell, the ultrasonic energy is transferred to the battery cell due to equipment reasons. The ultrasonic energy is very large. The internal diaphragm of the battery melts, and the positive and negative electrodes are directly shorted, resulting in an explosion.

4&#; Explosion during spot welding

During spot welding, if the current is too large, will cause a serious internal short circuit to explode. In addition, the positive electrode connecting piece is directly connected with the negative electrode during spot welding which will cause the positive and negative electrodes to explode after a direct short circuit.

5&#; Over-discahrge explosion

When battery be in stare of over-charging or over-discharging with the C-rate at 3C, it is easily for negative electrode copper to dissolve and deposite on thte diaphragm. This will cause short circuit and explode.

Do not worry. This phenomenon is rarely occur in our daily life.

6&#; Explosion in vibration and falls

When the battery vibrates violently or falls, the internal pole piece of the battery is misplaced, and it is directly severely shorted and explodes (rarely occurs).

After the lithium battery cell is overcharged to a voltage higher than 4.2V, side effects will begin to occur. The higher the overcharge voltage, the higher the danger. After the voltage of the lithium battery cell is higher than 4.2V, the number of lithium atoms remaining in the cathode material is less than half.

At this time, the storage cell often collapses, causing a permanent decrease in battery capacity. Since the storage cell of the negative electrode is already filled with lithium atoms, if charging continues, subsequent lithium metal will accumulate on the surface of the negative electrode material. These lithium atoms will grow dendritic crystals from the surface of the negative electrode in the direction where the lithium ions come.

These lithium metal crystals will pierce the diaphragm, shorting the positive and negative electrodes. Sometimes the battery explodes before a short circuit occurs. This is because during the overcharge process, the electrolyte and other materials will crack to produce gas which will cause the battery shell or pressure valve to bulge and break. It also allows oxygen to enter and react with the lithium atoms accumulated on the surface of the negative electrode, and then explode.

Featured content:
Who Makes the Best Lithium Batteries?
How to Choose the Right Stainless Pressure Fermenter?

For more information, please visit Lithium Battery Shell Seal Laser Welding Machine wholesaler.

Therefore, when charging lithium batteries, the upper voltage limit must be set. So that the battery life, capacity, and safety can be taken into account at the same time. The ideal upper limit of the charging voltage is 4.2V. There must also be a lower voltage limit when the lithium battery is discharged. When the cell voltage is lower than 2.4V, part of the material will begin to be destroyed.

Because the battery will self-discharge, the longer it is put on, the lower the voltage will be. Therefore, it is best not to charge it before 2.4V. During the period when the lithium battery is discharged from 3.0V to 2.4V, the energy released only accounts for about 3% of the battery capacity. Therefore, 3.0V is an ideal discharge cut-off voltage.

During charging and discharging processes, the current limit is also necessary. When the current is too high, the lithium ions will not have time to enter the storage cell and will gather on the surface of the material.

After these lithium ions obtain electrons, they will crystallize lithium atoms on the surface of the material, which is the same as overcharging and can cause danger. In case the battery shell breaks, it will explode. Therefore, the protection of lithium-ion batteries must include at least three items: the upper limit of the charging voltage, the lower limit of the discharge voltage, and the upper limit of the current.

Generally, in lithium battery packs, in addition to lithium battery cells, there will be a protection board. This protection board mainly provides these three protections. However, these three protections of the protection board are obviously not enough, and lithium battery explosions are still frequent around the world.

Conduct a more careful analysis of the causes of the battery explosion, and list some&#;

1. Large internal polarization&#;
2. The pole absorbs water and reacts with the electrolyte. Battery swells because of gas generated by reaction.
3. The quality and performance of the electrolyte itself&#;
4. When injecting liquid, the amount of liquid injected does not meet the process requirements.&#;
5. The sealing performance of laser welding in the assembly process is poor, and the air leaks when the air leaks are detected.&#;
6. Dust and pole piece dust can easily cause micro-short circuits in the first place.&#;
7. The positive and negative electrode pieces are thicker than the process range, making it difficult to enter the shell.&#;
8. The problem of liquid injection sealing, the poor sealing performance of the steel ball leads to the air bulge&#;
9. The incoming material of the shell has a thick shell wall, and the deformation of the shell affects the thickness.&#;
10.The external ambient temperature is too high, which is also the main cause of the explosion.

Want More Details: Download our battery design ebook.

With the rapid development of new energy vehicles and energy storage markets, the lithium-ion battery industry has ushered in rapid growth. Welding technology, as a key link in the production process of lithium-ion batteries, directly affects the performance and safety of batteries.

Traditional welding methods have problems such as large heat-affected zone, easy oxidation, and unstable welding quality. Laser welding has become the first choice for custom lithium battery pack welding with its unique advantages.

This article will focus on the laser welding machine for lithium ion batteries, hoping to be helpful for purchasing laser welding lithium ion batteries.

Battery Laser Welding Machine composition:

Features

• Controlled by PC, assisted by professional software, easy to operate and easy to learn;
• The large-format workbench can weld products of different sizes according to the actual production needs of the products, and multiple sets of fixtures can be installed, which is convenient and flexible.
• The processing is pollution-free, the heat-affected zone is small, the deformation is small, and the cooling medium can be purified to extend the life of the device and facilitate daily maintenance.
• The weld is fine, the depth is large, the taper is small, and the precision is high; the appearance is smooth, flat and beautiful.
• The perfect combination of high-definition coaxial visual CCD system and line light source fixed focus system makes welding line copying programming easier and more convenient.

Why Choose Laser Welding Lithium Ion Batteries

• High precision: Laser welding has extremely high energy density and precise focusing ability, achieving micron-level welding accuracy, avoiding thermal damage, and ensuring the structural integrity of the battery.
• Fast and efficient: Laser welding has a fast speed and a small heat-affected zone, which can greatly improve production efficiency and reduce production costs.
• High welding quality: The welds formed by laser welding are smooth and flat, without pores or cracks, with high welding strength and good reliability.
• Strong adaptability: It is suitable for welding a variety of materials, including copper, aluminum, nickel, etc., to meet the diverse welding needs of lithium-ion batteries.
• Environmentally friendly and clean: The laser welding process is pollution-free and meets environmental protection requirements.
• Non-contact process&#;Particularly suited for handling fragile components such as thin metal foils and tabs used in lithium-ion batteries. Non-contact minimizes the potential for equipment contamination and wear, helping to improve end-product quality with fewer defects.
• Automation and Integration: Highly compatible with automated production lines, it can achieve large-scale lithium-ion battery manufacturing. It speeds up production and ensures consistency. It reduces human errors and produces higher quality products.

Laser Welding in Li-ion Battery Manufacturing

Battery Tab Welding: Battery tabs are critical for conducting electrical current between cells. Laser welding ensures a reliable, high-strength connection between tabs and electrodes, preventing potential malfunctions or failures.

Enclosure Sealing: Battery enclosures need to be sealed to prevent exposure to moisture or air, which can degrade battery performance. Laser welding is ideal for sealing the aluminum or steel enclosures used in lithium-ion batteries due to its high precision and strong, clean welds.

Module and Pack Assembly: When multiple cells are assembled into a battery pack, laser welding ensures a secure electrical connection between cells. This improves the safety and performance of the entire battery pack.

Choosing the Right Battery Laser Welding Machine

1.Welding requirements analysis

Material

• Understand the material composition of lithium batteries, including positive and negative electrode materials, diaphragms, shells, etc. Different materials have different absorption and reflection characteristics of lasers, which will affect the welding effect.
• Metal materials such as aluminum and copper usually require higher-power lasers to achieve good welding.
• Consider the thickness of the material. Thinner materials may require lower-power lasers, while thicker materials require higher-power lasers to ensure the strength and sealing of the weld.

Welding requirements

Determine the precision requirements of welding. For welding that requires high precision, such as in the welding of micro batteries or electronic components, a laser welding machine with high resolution and high-precision positioning system should be selected.

Consider the strength requirements of welding. For lithium batteries that need to withstand large mechanical stress or are used in harsh environments, a laser welding machine that can provide high welding strength should be selected.

Evaluate the appearance requirements of welding. If there are high requirements for the appearance quality of welding, such as no pores, no cracks, smooth surface, etc., a laser welding machine with good welding quality control should be selected.

2.Laser welding machine parameters

Laser power

Choose the appropriate laser power according to the material thickness and welding requirements of the lithium battery. The higher the power, the faster the welding speed, but it may also cause overheating and material deformation. For thinner materials and high-precision welding, a lower-power laser may be more suitable.
Consider the stability of the laser power. Stable laser power can ensure the consistency of welding quality.

Laser wavelength

Different laser wavelengths have different absorption characteristics for different materials. Common laser wavelengths are nm, nm, etc. For the welding of lithium batteries, wavelengths with higher absorption rates for metal materials are usually selected.
Consider the stability and reliability of the laser wavelength. Stable wavelengths can ensure the consistency of welding effects.

Welding speed

Determine the appropriate welding speed according to production needs. Too fast welding speed may lead to a decrease in welding quality, while too slow will affect production efficiency.
Consider the dynamic performance of the laser welding machine, that is, the ability to maintain stable welding quality at different welding speeds.

Focused spot size

The focused spot size determines the welding accuracy and the size of the heat-affected zone. Smaller spot sizes enable high-precision welding, but also require higher power and a more precise positioning system.
Choose the appropriate focused spot size based on the welding requirements. For welding of micro batteries or electronic components, a smaller spot size is usually required.

3.Equipment performance and reliability

Equipment stability

Choose a laser welding machine with high stability and reliability to ensure long-term stable production. The stability of the equipment can be evaluated by examining the manufacturer&#;s reputation, product quality certification, and user reviews.
Consider the maintenance and care requirements of the equipment. Equipment that is easy to maintain and maintain can reduce production costs and downtime.

Control system

Advanced control systems can achieve precise welding parameter control and automated production. Choosing a laser welding machine with an intelligent control system can improve production efficiency and welding quality.
Consider the ease of use and operability of the control system. An easy-to-operate control system can reduce operator training time and error rate.

Safety performance

Laser welding machines are high-energy equipment, and safety performance is crucial. Choose equipment with complete safety protection measures, such as laser protection devices, emergency stop buttons, safety door locks, etc.
Ensure that the equipment meets relevant safety standards and regulatory requirements.

4.Manufacturer and after-sales service

Manufacturer reputation

Choose a laser welding machine manufacturer with a good reputation and rich experience. Well-known manufacturers usually have more reliable product quality and a more complete after-sales service system.
Learn about the reputation and strength of the manufacturer by consulting the manufacturer&#;s official website, product manuals, user reviews, and industry reports.

After-sales service

Good after-sales service can ensure the normal operation and timely maintenance of the equipment. Choose a manufacturer that provides comprehensive after-sales service, including equipment installation and commissioning, training, maintenance and technical support, etc.
Consider the response time and service quality of after-sales service. Timely response and high-quality after-sales service can reduce equipment downtime and production losses.

Conclusion

Choosing the right laser welding machine to weld lithium batteries requires comprehensive consideration of welding requirements, laser welding machine parameters, equipment performance and reliability, as well as manufacturers and after-sales services. By carefully evaluating and comparing different equipment options, you can choose the laser welding machine that best suits your production needs and improve the welding quality and production efficiency of lithium batteries.

Are you interested in learning more about Lithium Battery Shell Seal Laser Welding Machine China? Contact us today to secure an expert consultation!