A battery has two terminals (a positive (+) terminal and a negative (-) terminal).
Inside a battery is a solution called electrolyte.
An electrolyte is a solution that conducts electricity. It is a solution that contains free ions.
Because of that, sometimes an electrolyte is also called an ionic solution.
Examples of electrolyte are acids, bases and salts in solution.
See below to understand how a battery works
See Figure 1: 
Chemical formula for salt is NaCl. When salt dissolves in water, it produces free ions.
Positive ions are Na+ and negative ions are Cl-.
Negative ions (Cl-) are attracted to positive electrode called anode and positive ions (Na+) are attracted to negative electrode called cathode.
At the positive electrode, negative ions give up electrons that flow through the bulb and light it up and then return to the negative electrode.
At the negative electrode, positive ions take electrons.
This results in a continuous flow of electrons in the circuit and a continuous flow of ions in the electrolyte solution.
The continuous flow of electrons and ions produces electricity and electricity only occurs when there is a complete circuit or path.
The same process happens inside a battery in Figure 2.
At the positive electrode, negative ions give up electrons that flow through the bulb and light it up and then return to the positive terminal of battery.
At the negative electrode, positive ions take electrons.
This results in a continuous flow of electrons in the circuit and a continuous flow of ions in the electrolyte solution.
Electrons come out of the negative terminal (-) of a battery and flow around the circuit and re-enter the positive terminal (+) of a battery.
The continuous flow of electrons and ions produces electricity and electricity only occurs when there is a complete circuit or path.
How a battery works?
The Magic of a Battery
What is a battery?
A battery is a device that provides electricity to make our clock ticking, our electronic toy moving, our torch lighting up, our hand phone ringing and so forth.
A battery has two terminals. A positive terminal is marked with a + symbol and a negative terminal is marked with a – symbol.
Electrons come out of the negative terminal (-) and flow around the circuit and
re-enter the positive terminal (+).
The flow of electrons in a complete circuit provides us electricity and make us able to talk to our friends through a hand phone, see things at night by using a torch light and so forth.
You need two wires, a battery and a bulb to see a battery works as magic.
When the wires are connected in a complete circuit as shown, the bulb will light up.
