The lithium-ion batteries (Li-ion) are, in general, extremely safe. But we often read about various explosions, like the Samsung Galaxy Note 7 fixture or the latest recall from HP laptops. But what happens to these batteries?
Rechargeable Li-ion batteries are the batteries we come across in laptops, smartphones, tablets and just about every other gadget you have. What we do on airplanes and electric cars. Without the lithium-ion batteries, we could not do much of what we do in places without sockets.
What's inside a lithium-ion battery?
To understand why we sometimes hear about explosions in Li-ion batteries, you need to know their structure. Inside each lithium-ion battery, there are two electrodes, the positively charged cathode and the negatively charged anode, separated by a thin sheet of "micro-permeable" plastic that holds the two electrodes apart without touching them.
When charging a lithium-ion battery, lithium ions push electricity from the cathode, through microwaves to the separator, into an electrically conductive liquid, and to the anode. When the battery is discharged, it is exactly the opposite with the lithium ions that flow from the anode to the cathode. This is the reaction that gives energy to your laptop.
Small batteries, such as those on smartphones, usually have only one lithium-ion cell. Larger batteries, such as laptops, usually have between 6 and 12 lithium-ion cells. Batteries in electric cars and airplanes can have hundreds of cells.
What makes a lithium battery explode?
The same thing that makes lithium-ion batteries as useful is what gives them the ability to catch fire or explode. Lithium is very good for energy storage. When released slowly, it fills your phone all day long. But when released at once, the battery may explode.
Most fires and explosions of lithium-ion batteries are referred to as a short circuit problem. This happens when the plastic separator fails to separate the rise and fall. And of course when they meet, the battery starts to overheat.
There are several reasons why the separator may fail in his work:
Bad design or manufacturing defects: The battery is not properly designed, as was the case with the Galaxy Note 7. In this case, there was not enough space for the electrodes and the battery separator. On some models, when the battery heats up slightly as it charges, the electrodes bend and cause a short circuit. Even a well-designed battery can fail if quality control is not followed with "reverence" or if there is a defect in the construction.
External factors: Extreme heat almost guarantees some battery failure. Batteries that stay close to a heat source are known to explode. Another external factor that can cause the failure of a lithium-ion battery. it is if your device is dropped several times. This may cause damage to the separator and cause the electrodes to contact. If you pierce the battery (accidentally or deliberately), you will almost certainly cause a short circuit.
Charger problems: A poorly built or poorly insulated charger can also damage a lithium-ion battery. If the charger produces heat near the battery, it can cause damage.
Thermal leakage and multiple cells: This issue is not related to single cell batteries, such as those in most smartphones (the iPhone X actually has two cells).
Once a cell overheats, we may have a domino effect called "thermal escape" or "thermal runaway." For batteries with hundreds of cells, such as those of the Tesla Model S, a heat leak can be a really big problem.
