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Electricity > Electrical Cell Chemistry

An electrical cell is essentially two metals which sandwich an electrolyte (a liquid with free moving ions). If you connect more than one cell, you create a battery.

The tables below show typical metals and electrolytes used in some cells. Primary cells are used in standard batteries. The chemical reaction which takes place within is one way, meaning that when the chemicals are used up, the battery ceases to provide electricity.

Batteries which use secondary cells are rechargeable because the reaction is reversible. If the potential difference is applied to the battery from an external source, the reaction runs in reverse, recharging the battery.

Primary Cells

Example Cathode (−) Electrolyte Anode (+)
voltaic pile
(1799)
zinc
(Zn)
brine
(saltwater)
copper
(Cu)
daniell cell
(1836)
zinc
(Zn)
zinc sulphate (ZnSO4)
copper sulfate (CuSO4)
copper
(Cu)
leclanché cell
(1866)
zinc
(Zn)
ammonium chloride
(NH4Cl)
manganese dioxide
(MnO2)
dry cell zinc
(Zn)
manganese dioxide
(MnO2)
carbon
(C)
lemon zinc
(Zn)
citric acid
(C6H8O7)
copper
(Cu)

Secondary Cells

Example Cathode (−) Electrolyte Anode (+)
lead acid lead
(Pb)
sulfuric acid
(H2SO4)
lead oxide
(PbO2)
Ni-cad nickel hydroxide
(Ni(OH)2)
potassium hydroxide
(KOH)
cadmium hydroxide
(Cd(OH)2)
nickel metal hydride nickel
(Ni)
potassium hydroxide
(KOH)
intermetallic compounds