Are 18650 batteries safe? Violent dismantling of 18650 batteries

The 18650 battery is a cylindrical battery with a diameter of 18mm and a length of 65mm with a cylindrical package. In addition to the most common cylindrical packaging method, the lithium batteries on the market are the most widely used in the field of notebooks and strong light flashlights. The advantages of this type of packaging are uniform specifications, convenient for automation and large-scale production; in addition, there are Prismatic square soft package packaging, which is common For mobile phones and tablet computers, the most direct benefit of this type of package is lightness and thinness.

Many netizens talked about 18650 batteries, worrying about the 'liquid lithium ion' inside, and 'talking about 18650 discoloration' panicked and exploded. To this end, the author violently dismantled an 18650 battery cell in his hand, and explored what happened inside. First of all, remember to discharge the battery when disassembling the battery. Here, the 18650 battery is discharged until it fails and there is no voltage.

Then, use needle-nose pliers to violently tear open the cap position of the battery cell to separate the positive and negative steel shells, exposing the safety valve and the positive and negative materials of the package.

The safety valve is the standard configuration of every 18650 battery cell, and it is also the most important explosion-proof barrier. There is no one. The working principle of the safety valve: When the internal temperature of the battery is abnormal and the air pressure rises to 1.0-1.2Mpa, the safety valve opens to remove the internal gas to avoid explosion caused by excessive pressure. And Prismatic square soft-packed batteries, when the internal pressure rises, the most common phenomenon of 'pregnancy' bulge.

Here, popular science is about the positive pole inside the battery. Now the common 2000-3000mAh capacity batteries such as Samsung, Panasonic, Sanyo, LG, etc., the internal cathode material has been fully upgraded from the first generation LiCoO2 lithium cobalt oxide to a ternary material, the chemical name is LiNi-Co-MnO2 nickel Cobalt manganese. The direct benefits: longer service life, safer and better performance. Speaking of this, the Prismatic square soft package packaged mobile phone tablet batteries are also made of LiNi-Co-MnO2 nickel-cobalt-manganese material, but it is different from the 18650 Cylindrical package.

Finally, take a close-up of the materials inside the cell. The copper foil in the picture is used to coat LiNi-Co-MnO2 nickel-cobalt-manganese cathode material, on the contrary, aluminum foil is used to coat graphene. The capacity of the battery cell is based on the blending ratio of these formulas. Imitation is risky, and disassembly needs to be cautious.

Conclusion: After violently dismantling the 18650 battery cell, it was found that there was no liquid flowing out of the battery, so there is no saying that 'liquid lithium ion' is easy to explode. In fact, under normal circumstances, as long as it is used correctly, without charging or encountering extreme environments, 18650 batteries will not cause safety hazards.