Batteries can be classified according to their chemistry or specific electrochemical composition, which heavily dictates the reactions that will occur within the cells to convert chemical to electrical energy. Battery chemistry tells the electrode and electrolyte materials to be used for the battery construction.
Usually a battery is made up of cells. The cell is what converts the chemical energy into electrical energy. A simple cell contains two different metals (electrodes) separated by a liquid or paste called an electrolyte. When the metals are connected by wires an electrical circuit is completed. One metal is more reactive than the other.
Every battery is basically a galvanic cell where redox reactions take place between two electrodes which act as the source of the chemical energy. Batteries can be broadly divided into two major types. Based on the application of the battery, they can be classified again.
The key distinction lies in the rechargeability of secondary batteries, as opposed to primary batteries, which cannot be recharged. The reactions in primary batteries cannot be easily reversed. As such, when the battery electrodes are used up, they cannot be reverted back to their original state even when an external voltage is applied.
The most studied batteries of this type is the Zinc-air and Li-air battery. Other metals have been used, such as Mg and Al, but these are only known as primary cells, and so are beyond the scope of this article.
Battery chemistry tells the electrode and electrolyte materials to be used for the battery construction. It influences the electrochemical performance, energy density, operating life, and applicability of the battery for different applications. Primary batteries are “dry cells”.