Tables 2a, b, c and d summarize the composition of lead-, nickel- and lithium-based secondary batteries, including primary alkaline.

The cathode of a battery is positive and the anode is negative.

(See BU-212: Future Batteries) With few exceptions, lithium-metal batteries are non-rechargeable. Here the cathode is carbon and the anode metallic lithium. The anode of Li-ion is carbon (See BU-204: How do Lithium Batteries Work?) but the order is reversed with lithium-metal batteries. Since the battery is an electric storage device providing energy, the battery anode is always negative. A vacuum tube, diode or a battery on charge follows this order however taking power away from a battery on discharge turns the anode negative. This appears to violate the convention as the anode is the terminal into which current flows. The battery anode is always negative and the cathode positive. The electrode of a battery that releases electrons during discharge is called anode the electrode that absorbs the electrons is the cathode. The separator electrically isolates the electrodes but allows the movement of ions. Ions are atoms that have lost or gained electrons and have become electrically charged. On charge, the current flows in the other direction.Ī battery has two separate pathways one is the electric circuit through which electrons flow, feeding the load, and the other is the path where ions move between the electrodes though the separator that acts as an insulator for electrons. Release is by a passing current from the positive cathode through an external load and back to the negative anode. This leads electrons moving towards the cathode, creating a voltage potential between the cathode and the anode. When charging, a buildup of positive ions forms at cathode/electrolyte interface. An electrochemical battery consists of a cathode, an anode and electrolyte that act as a catalyst.

Cathode anode