Electric Vehicles - Batteries

As can be seen in the above list, the three main batteries employed today are lead-acid; nickel-metal hydride; and lithium-based batteries. Of these, experts predict nickel-metal hydride and lithium-based batteries have the greatest potential.

The lead acid battery uses lead oxide and spongy lead electrodes with sulfuric acid as an electrolyte. Generally, they consist of several cells put in series to form a battery, such as an automobile battery. The group of cells are generally in a polypropylene container. The advantages of the lead-acid battery are commercial availability, recyclability and low cost. The disadvantages are that they are heavy and the amount of energy stored per kilogram is less than other types of batteries.

Nickel-metal hydride operates by moving hydrogen ions between a nickel-metal hydride cathode and a nickel hydroxide anode. During discharge, hydrogen moves from cathode to anode. During charging, ions move in the opposite direction.

There are two types of lithium batteries, the lithium ion and the lithium polymer. A lithium ion type works by dissolving lithium ions, and transporting them between the anode and cathode. The battery has an anode made of lithium cobalt dioxide and a cathode from a non-graphitizing carbon. During operation, lithium ions move through a liquid electrolyte that contains a thin, microporous membrane. The lithium polymer uses lithium as an electrochemically active material and the electrolyte is a polymer or polymer-like material that conducts lithium ions.