Do lithium-ion batteries explode easily?

As long as it is a lithium battery, there is a risk of explosion, but this is a small risk probability. But once it explodes, the power of the lithium battery with a larger capacity will be more and more explosive.

Calculate, a fully charged 2.6AH 18650 ternary lithium battery with a charge of 2.6*3.65*3.6=34.164 kJ. The energy generated by the muzzle of a general pistol is about 2.2 kilojoules. 1 joule is equivalent to the work done when the force of 1 Newton moves the object in the direction of force by 1 meter, so within 50 meters of the pistol, You can easily kill enemies. Think about it, a Tesla needs to use more than 7,000 3.4AH 18650 lithium batteries.

An important cause of battery explosion is the short circuit of the battery (that is, there is no electrical appliance in the circuit where the battery is located, so that the current inside the battery is too large), and whether the battery is short-circuited or overcharged (the lithium battery explodes another An important incentive, that is, the battery charging voltage is higher than its set upper limit, will cause a large amount of heat and gas to accumulate inside the lithium battery in a short time (the lithium battery will generate gas when it works), so that in order to release the pressure, The lithium battery will either activate the internal pressure relief device. If the pressure is too high, it will directly crack the outer casing. In both cases, the internal material of the battery will directly contact the air, causing combustion, and in severe cases, it will explode. All in all, it is the heat out of control.

As mentioned earlier, lithium battery explosion has two important causes, one is short circuit and the other is overcharge. The short circuit is easy to understand, that is, the battery is directly in contact with the positive and negative electrodes. First, in a short period of time, the heat generated by a short circuit in a small area is actually very small, and will not cause thermal runaway. The battery core itself is designed with an explosion-proof valve, which means that when the internal pressure of the battery exceeds a certain value, the explosion-proof valve will be opened and the heat will quickly dissipate. The second is that the normal battery charging device is protected against overcharging, and will stop charging when the battery voltage reaches a certain value. The third core itself is a steel shell and has good protection.

Will not explode

Lithium polymer batteries use a gas for a long time, so they will swell.

At a certain level, the sealing of the battery case will leak, so it is still not good.

Why use a lithium-ion battery? Lithium-ion batteries have many advantages over other types of rechargeable batteries, the most important of which is its energy density. The electrodes of lithium-ion batteries are generally composed of lithium compounds and graphite (pure carbon), both of which are very light materials. The lithium is also a very reactive element, so more atoms can be stored in the bonds. Adding them together means that it is in the existing rechargeable battery, if you want to have the same amount of stored electricity, the lithium-ion battery is the lightest, suitable for mobile phones, laptops, digital cameras and other portable items. In addition, lithium ions have no memory effect, which means that lithium-ion batteries do not need to first discharge the power to recharge, and the storage capacity will not decrease too much, about 0.1% of electricity per month (counting the need for protection loops) Only 5%, nickel-metal hydride batteries are reduced by about 20% per month). Finally, it can still be used for hundreds of times of charging and discharging.

However, lithium-ion batteries also have disadvantages. The most important one is that its total storage power (maximum power) will decrease with the increase of the factory time--even if you do not use lithium-ion batteries, the maximum storage power of the battery will be greatly reduced after 2~3 years. Unable to use, so "buy and put" is completely wrong. Secondly, lithium-ion batteries are very hot, and the effect of reducing the maximum amount of stored electricity in a high-temperature environment will be accelerated. This part will be supplemented later. In addition, lithium-ion batteries are also afraid of over-discharge. Once the discharge exceeds a certain level, the power may no longer be charged. Of course, lithium-ion batteries also have the danger of exploding, which is known to everyone.

Why does a lithium-ion battery explode? This should be discussed from its chemistry... Lithium-ion battery chemistry Xiao Jiang is not too deep in this place (in fact, it is not completely understand orz), but in simple terms, lithium-ion battery is the same as all rechargeable batteries. There is a positive electrode material and a negative electrode material, where the positive electrode material is usually lithium cobalt oxide (LiCoO2), and the negative electrode material has many kinds, the most common graphite (carbon). During charging, the lithium ions in the lithium cobalt oxide will swim through the intermediate electrolyte and adhere to the negative electrode, while the discharge (above) is the opposite, from the carbon of the negative electrode to the side of the lithium cobalt oxide.

In a lithium-ion battery with graphite as the negative electrode, a layer of lithium cobalt oxide, a layer of electrolyte containing a layer of graphite, and a layer of graphite are used in a group. In the thin battery of the mobile phone battery, the inside is such a layer, and in the notebook, the material of the piece is usually rolled into a cylindrical shape, which becomes a thing like the No. 3 battery. In lithium-ion batteries, it is not the two electrodes that have the greatest danger, but the organic electrolyte solvent in the middle, with the most flammable ethers. When the battery is short-circuited for any reason, the energy in the battery will be released in the form of heat for a short period of time, igniting these ethers as solvents, causing an explosion.

During over discharge, lithium ions react directly with lithium cobalt oxide to produce lithium oxide and cobalt oxide. This reaction is irreversible, so a lithium-ion battery that is over-discharged is equivalent to reimbursement.

Is a lithium-ion battery very easy to explode? The experience I got at ITRI was: "How is it so difficult!" At the ITRI, they installed a machine that pierced the flat battery with a drill bit. Basically, it must be new and fully charged. The battery has the greatest explosion hazard. As long as it is used for a period of time, not only the maximum voltage will be greatly reduced, but also the materials used inside will be "passivated" and become less reactive. We prepared a lot of old batteries ready to explode. What we didn't expect was that not only all the old batteries didn't explode, but even the new batteries didn't have to explode. Does this mean that it is safer to buy a second-hand battery? XD

But the explosion is one thing. We still see a very terrible temperature from the thermometer on the probe. After the battery is short-circuited, the internal temperature is often above 100 degrees. It is impossible to be so comfortable in a trouser pocket.

What are the safety measures for lithium-ion batteries? In order to avoid overheating or even explosion of lithium-ion batteries, modern lithium-ion batteries have many self-protection mechanisms. First, each lithium-ion battery (or in the case of a laptop, the entire battery pack) has a built-in control chip that monitors the battery voltage (the battery pack monitors each of the batteries). The individual voltage) and temperature, beyond the set range, the chip will automatically power off. In addition, each battery is also designed with venting holes, so that the gas generated by the high temperature can be smoothly discharged without accumulating an explosion.

These protections are sufficient for batteries that are not physically damaged, but what if they are damaged (eg puncture) lithium batteries? This is the strength of the newly developed STOBA battery from the Institute. The STOBA battery incorporates a "nano-grade polymer material" in the electrolyte. When heated, the polymer material polymerizes into a film with a barrier effect, prevents the flow of lithium ions, and cuts off the short-circuit battery. Continue to heat the battery. This technology not only prevents the battery from exploding, but also prevents the battery from overheating. Most of the experiments we have seen do not exceed 60 degrees Celsius - it will still be hot, but at least there is no danger of igniting surrounding combustibles.

The other two factors that affect the reduction of electricity storage are temperature, and second, the battery is full. No matter what you do (or don't do), the total storage capacity of the lithium battery is constantly decreasing, but the high temperature and full charge will accelerate the decline. Therefore, buying a less enthusiastic notebook, not only has positive help for fertility, but also helps to slow down the battery's storage capacity. In addition, if the computer has the relevant settings, charging the battery to eight minutes can reduce the speed of the storage capacity to half - meaning that if you charge the battery every time, you can run for 4 hours a year later. The computer can only run for 2 hours, then only charge the battery to eight minutes each time, and the computer can run for 3 hours after one year.

The electrodes of lithium-ion batteries are generally composed of lithium compounds and graphite (pure carbon), both of which are very light materials. The lithium is also a very reactive element, so more atoms can be stored in the bonds. Adding them together means that it is in the existing rechargeable battery, if you want to have the same amount of stored electricity, the lithium-ion battery is the lightest, suitable for mobile phones, laptops, digital cameras and other portable items. In addition, lithium ions have no memory effect, which means that lithium-ion batteries do not need to first discharge the power to recharge, and the storage capacity will not decrease too much, about 0.1% of electricity per month (counting the need for protection loops) Only 5%, nickel-metal hydride batteries are reduced by about 20% per month). Finally, it can still be used for hundreds of times of charging and discharging. However, lithium-ion batteries also have disadvantages.