Modern Physics
 
   
  The way these new age batteries work is very impressive, the ability to discharge and recharge is an enormous leap from the original battery created.
 
  The concept of a battery is when the battery is connected to an item or object to power it, it gives off electrical energy. This reaction that occurs is called an electrochemical reaction. According to the Encyclopedia Britannica an electrochemical reaction is "any process either caused or accompanied by the passage of an electric current and involving in most cases the transfer of electrons between two substances". So within the batteries reactions happen within the anode and cathode in order to produce the electric current used to run the appliances. The anode creates electrons while the cathode takes the electrons and absorbs them. Now for when needing to recharge a battery a different process occurs. A current is to the cathode instead of the anode and then the cathode releases electrons and the anode absorbs the electrons. Once this is done the anode can then once again creates more electrons and the cathode can then absorb them once more allowing one to power something using the battery.  
 
http://electronics.howstuffworks.com/everyday-tech/lithium-ion-battery1.htm