what makes a battery work
The trick in a battery is to separate the oxidation from the reduction, so the electrons have to go on a trip through the external circuit, where we can make use of them. Oxidation and reduction reactions make a battery work. Oxidation/reduction reactions are electron-transfer reactions. For a battery to work, both an oxidation and a reduction must happen. One generates electrons at one electrode, and the other uses them up at the other electrode.