The lithium-ion batteries (Li-ion) are generally extremely safe. But very often we read about various explosions, as then with the fiasco Galaxy Note 7 της Samsung ή με την πιο πρόσφατη ανάκληση των φορητών υπολογιστών της HP. Τι συμβαίνει όμως με τις συγκεκριμένες μπαταρίες;
The rechargeable ones lithium-ion batteries (Li-ion), are the batteries found in laptops, smartphones, tablets and almost every other gadget you have. What we find in airplanes and electric cars. Without lithium-ion batteries, we wouldn't be able to do much of what we do in places that don't have power outlets.
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 you charge a lithium-ion battery, the lithium ions push electricity from the cathode, through micro-holes in the separator, into an electrically conductive liquid, and to the anode. When the battery discharges, the exact opposite happens with lithium ions flowing from the anode to the cathode. This is the reaction that powers your laptop computer.
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.
