Some Commercial Cell(Batteries)
One of the main use of galvanic cells is the generation of portable electrical energy. These cells are also popularly known as batteries. The term battery is generally used for two or more Galvanic cells connected in series. Thus, a battery is an arrangement of electrochemical cells used as an energy source. The basis of an electrochemical cell is an oxidation – reduction reaction.
Types of commercial cells: There are mainly two types of commercial cells,
(1) Primary cells: In these cells, the electrode reactions cannot be reversed by an external electric energy source. In these cells, reactions occur only once and after use they become dead. Therefore, they are not chargeable. Some common example are, dry cell, mercury cell, Daniell cell and alkaline dry cell
(i) Voltaic cell
Cathode : Cu rod Anode :Zn rod
Electrolyte :dil. 
Emf :1.08 V
At cathode :
At Anode :
Over all reaction :
(ii) Daniel cell
Cathode : Cu rod Anode :Zn rod
Electrolyte :dil. Emf :1.1 V
At cathode :
At Anode :
Over all reaction :
(iii) Lechlanche cell (Dry cell)
Cathode: Graphite rod
Anode:Zn pot
Electrolyte:Paste of 
in starch
Emf:1.2 V to 1.5 V
At cathode : 
At Anode :
Over all reaction :
(iv) Mercury cell
Cathode :Mercury (II) oxide
Anode :Zn rod
Electrolyte : Paste of 
Emf :1.35 V
At cathode :
At Anode :
Over all reaction :
