Introduction

Lithium is the most reactive metal in the world. Lithium-ion batteries are the first choice for electric vehicles because they are small in size, high in density, and high in energy density. In the operation of lithium-ion batteries, using lithium ions to gain and lose electrons, migrate and accumulate them, so as to realize the storage of electric energy. However, lithium-ion batteries are extremely sensitive to high temperatures and are inherently spontaneously combustible. Due to heat, the degradation rate of these batteries is often much faster than normal. If the lithium-ion battery pack breaks down, it will catch fire and cause extensive damage. This passage would list the main reasons in regards to why lithium-ion batteries spontaneously combust and provide some tips to avoid this situation happen.

Reasons Cause the Lithium-Ion Batteries Spontaneously Combust

Combustion or explosion usually occurs due to the battery can heat up to the point where the heat is out of control. Accumulation to the point of fire, or heat accumulation in a certain space to a certain extent will happen. As a lithium-ion battery, it is attributed to the following four reasons.

First of all, excessive moisture content. Moisture can react with the electrolyte in the battery to generate gas. When charging, it can react with the generated lithium to generate lithium oxide, which will lead to the loss of the battery cell capacity. The battery is easy to overcharge to produce gas and decompose the water. The voltage is low, and it is easy to decompose to produce gas when charging. When this series of gas will increase the internal pressure of the battery, the battery will explode when the shell of the battery can’t bear it. 

Secondly, overcharge the lithium-ion battery. This is the most dangerous and fearful thing for enterprises, but it still happens occasionally. From the understanding, there are two points: one is the user does not use the matching charger as required, thus destroying the protection circuit, and the user often charges indefinitely. This situation is not difficult to break out; the other is the battery configuration is unreasonable, and the protection plate is faulty. In this case, it will be a mess.

Thirdly, it has an internal short circuit in the lithium-ion battery. Structural or technological defects lead to electrode ear interpolation, too little film wrapping allowance, burrs, and film discounts. The insertion of tabs often occurs in the structure and the internal parallel connection of thick batteries. The insulation of the lugs is not in place. It is easy to cause an internal acute short circuit in the subsequent finished product with a protective plate or in the process of use. This may cause burning or explosion, but now it is almost rare unless it is an external factor. 

Last but not least, external short circuit. It is rare for a battery below 1 AH to explode after burning, which usually bulging or simply burning out the tab. Analysis shows that the external short circuit of the power battery or large-capacity mobile phone battery causes burning. This involves improper use by the customer-the insulation of the tab is not considered when installing the metal outer box, and the battery on the installation site smokes and burns abnormally; the power battery also has common structural fixing measures. The external insulation of batteries is caused by the shaking of the battery pack when users use them, and the protective film is damaged or the outer skin of connecting wires is damaged, which eventually leads to short-circuit burning.

How to Avoid

Minimize the Risk of Lithium-Ion Battery Spontaneously Combust

As the above mention, if the battery is exposed to high temperature, or the battery or internal components are damaged, the risk of fire or explosion will increase. There are several ways you can reduce the risk of an accident.

Avoid storage at high temperatures. 

When the battery is close to the heat source, the flammable electrolyte inside the battery will cause a fire. The battery is easy to overheat and cause electrolyte evaporation. The evaporation produces combustible steam, and if the temperatures continues to rise, these steam will ignite. Do not put the batteries in hot vehicles. Don’t let the blanket cover the notebook computer.

Avoid putting all items with lithium-ion batteries together. 

When you travel, especially on the plane, you’ll put all your electronic products in one bag. This is inevitable because the batteries must be put in your carry-on, but usually, you can leave some space between the items with the battery. Although placing lithium-ion batteries nearby will not increase the risk of a fire, if an accident occurs, the other batteries can catch fire, making the situation worse.

Avoid overcharging the batteries. 

These batteries can be discharged and recharged many times nearly back to their original charge because they do not suffer the “memory effect” as badly as other types of rechargeable batteries. However, if they are completely drained before recharging or are over-charged, they do not farewell. Besides, using a charger with poor insulation can damage the battery. If the charger is short-circuited or heats up near the battery, it can cause enough damage, failing. Although lithium-ion batteries have built-in protections against overcharge, using unofficial chargers can damage the battery for a long time.

Protect yourself when the lithium-ion battery spontaneously combust. 

If you notice that the lithium-ion battery is overheated, please try to keep the equipment away from flammable materials and cutting off the power supply. If you are in an electric car, you should evacuate immediately, and never try to extinguish the fire of lithium-ion battery by yourself. Your health and safety are much more important. Call emergency services.

Conclusion

The reasons cause the lithium-ion batteries spontaneously combust are excessive moisture content, overcharge the lithium-ion battery, internal short circuit, and external short circuit. Luckily, major explosions caused by lithium-ion batteries are an uncommon occurrence. But we still need to take measures to minimize the risk of lithium-ion batteries spontaneously combust. As we use more and more electronic and rechargeable devices with lithium-ion batteries, it’s important to keep safe!

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