Batteries
1.1 Primary Batteries
Primary batteries are batteries in which the redox reaction occurs only once and after significant period of time battery becomes useless and cannot be reused again. A dry cell or Leclanche cell is one such example of a primary battery.
Construction:
1. A zinc container ( also acting as anode)
2. A Graphite (acting as a cathode) surrounded by powdered manganese dioxide and carbon
3. Ammonium chloride (NH4Cl) and zinc chloride (ZnCl2) paste filling the entire volume
Working:
Redox reactions that take place are:
1 At anode side : 
2.At cathode side : 
This cell has a potential of 1.5 V. (approx)
1.2 Secondary Batteries
A secondary cell is a cell which can be used again and again. It can be recharged by passing current through it in the opposite direction. Normally it can undergo a large number of discharging and charging cycles.
A simplest example is a lead storage battery.It is most commonly used in automobiles and invertor applications.
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