Why do electronic devices’ batterys start swelling at some point?

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To clarify, those devices which have a battery in them, for example phones and laptops.

In: Technology

Lots of different reasons. Could be a manufacture defect, could be contamination, certain reaction could gas to form contribute to bloating, heat can cause certain gases to expand etc.

Lithium batteries, like most batteries, work using chemical reactions to store and release energy. If the battery gets too old, too hot, charged to much or too quickly, or a few other things, the chemical reaction changes to one that produces gases, usually carbon dioxide and carbon monoxide. Being a gas, it has a much larger volume than the solids and liquids in the battery, so it puffs up the battery, like blowing into a paper bag.

The swelling is a sign that the battery is dangerously deteriorated and shouldn’t be used. Lithium batteries are dangerous when they catch fire.

Batteries run on chemical reactions. A battery that’s behaving properly doesn’t swell but if something goes wrong with the reaction (temperature regulator fails, too much current forced into the battery, internal short circuit, etc.) then you can get a lot more energy released in the battery that it was intended to. That can boil the electrolyte and release other funky gases from the chemicals in the battery, which all takes up more space than the original chemicals. And, since the battery is mostly sealed, that pressurizes the inside of the battery and makes it swell.