The working principle of Lead-Acid Batteries is based on the redox reaction of lead and lead dioxide in a sulfuric acid electrolyte. Specifically, during discharge, lead reacts with sulfuric acid at the negative electrode to produce lead sulfate and hydrogen, while lead dioxide reacts with sulfuric acid at the positive electrode to produce lead sulfate, water and electrons. These two reactions together produce an electric current, thereby directly converting chemical energy into electrical energy.