Can jackfruit be an alternative battery?

Answer 1

Anything containing an electrolyte (salt, acid, or base in water or the molten state) can be used to make a battery by placing two different metal plates in it. It won't be all that good a battery though compared to ones you can buy.

Any fruit, vegetable, piece of meat, etc. can be used. You could even make a pair of cuts in your arm or leg and insert one plate in each and it will work (but I REALLY DON'T RECOMMEND trying this, a really bloody steak from the store would be reasonable though instead).

The batteries that operate most modern nuclear weapons are "thermal batteries" using a solid salt that becomes an electrolyte when in the process of arming a chemical reaction is triggered that heats the battery, melting the salt inside it. These batteries have a shelf life estimated in centuries, the longest of any battery made, allowing the weapon to always be ready if needed.