eli5 Why can some batteries be recharged and others can’t?
In: Chemistry
Mainly chemistry and safety.
Some batteries are designed so that the chemistry can work in reverse. After the battery is used and discharged, we can apply a controlled voltage to make some of the chemical reactions work in the opposite direction.
Some batteries are not made that way. When the battery is discharged, the chemical changes that happen are permanent. We can’t undo those reactions – or we can’t undo them safely.
It’s because of the different materials in the battery and mechanisms.
Rechargeable batteries like AA batteries or phone batteries have special chemicals inside that can be “recharged” by pushing electricity back into them. This reverses the chemical process that powers the battery.
Non-rechargeable batteries like AAA or 9V batteries have chemicals that get used up completely as the battery runs down. Once those chemicals are all used up, you can’t recharge or reverse that process.
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