Working of a battery : 

• A battery consists of two metal plates (positive electrode = anode and negative electrode = cathode) and a chemical (electrolyte). 
• The electrolyte between the two metal plates consists of positive and negative ions which move in opposite directions.
• The electrolyte exerts a chemical force on these ions and makes them move in a specified direction. 
• Depending upon the nature of the chemical, positive ions move towards one of the plates and accumulate on that plate. 
• As a result of this accumulation of charges on this plate it becomes anode. 
• Negative ions move in a direction opposite to the motion of positive ions and accumulate on the other plate. 
• As a result of this the plate becomes negatively charged called cathode. 
• This accumulation of different charges on respective plates continues till both plates are sufficiently charged. 
• But the ions in motion experience electric force when sufficient number of charges are accumulated on the plates.
• The motion of ions continues towards their respective plates till the chemical force is equal to electric force. 
• Thus the battery works.