Difference between primary and secondary battery ?

You know about non-chargeable batteries and rechargeable batteries. The non – chargeable batteries are those which can be used once and after its life span it has to be thrown off. Whereas rechargeable batteries can be used repetitively by recharging them with electric energy. The non-chargeable batteries are generally referred as primary batteries where as the rechargeable batteries are referred as secondary batteries. The secondary batteries are also known as storage batteries. Actually in primary battery cells, the chemical reactions responsible for delivering electrical energy, are irreversible. Once the reactions are completed there is no provision of reversing them. On the other hand a secondary cells can be recharged for making them ready for next operation. That means the chemical reactions take place inside the secondary cells are reversible. When load is connected to the secondary batteries, the forward reactions take place in the chemical of the battery for delivering electrical power to the load. This process is known as discharging of battery.

Again when the secondary batteries are connected to the external electrical source, the chemical inside the batteries react in reverse way and the batteries become ready for next discharging operation. This process is known as charging of battery.
Generally, primary cells are low in cast and easy to store and easy to use. Mainly carbon-zinc batteries and Alkaline Batteries predominate the market of primary battery. Although where very tiny current, long service life and very small size are required, Mercury based and Lithium based batteries are used.
Secondary or rechargeable batteries are widely used in industrial and automotive applications. Actually secondary cells are preferred to be used where the user are ready to pay higher initial cost to ensure high current delivery in a consisting and reliable manner. Lead acid and nickel cadmium batteries mainly used for commercial applications. Nickel-hydrogen and silver zinc secondary batteries are used where performance requirements are more important than installation and maintenance cost.