How does the battery work?

Batteries have three parts: anode (-), cathode (+) and electrolyte. The cathode and anode (the positive and negative sides on both ends of a traditional battery) are connected to an electrical circuit. Chemical reactions in the battery lead to the accumulation of electrons at the anode. This results in an electrical difference between the anode and cathode. You can think of this difference as an unstable build-up of electrons. The electrons want to realign themselves to get rid of this difference. But they do it in a certain way. The electrons repel each other and try to get to the place with fewer electrons.