- All batteries work rely on the electrochemical reaction between two substances joined by an electrolyte. These two substances are electrodes, called the cathode and the anode. When power is drawn from the battery, charged particles flow from the anode to the cathode. Car batteries are all of the lead-acid design.
-
In the lead-acid design, the anode and cathode are made of lead and lead dioxide. The electrolyte is a solution that is 1/3 sulphuric acid. As power is discharged from the battery, both the anode and cathode undergo a chemical reaction that turns them into lead sulfate. The two electrodes are physically separated by a non-conductive barrier to prevent contact and a short-circuit.
The lead acid design is more than 150 years old, and they are among the biggest and heaviest batteries around, with awful size and weight-to-power-output ratios. However, the design continues to be used because of its main advantage: the ability to give a big surge of electricity. - When current is applied to a lead-acid battery, the electrochemical reaction is reversed. Current flows into the battery through the anode, and the anode and cathode partially reverse their mutual conversion into lead sulfate.
