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 |