Applications of Electrochemical Cells: Batteries

1

• Applications of Electrochemical Cells (Batteries)

• The Dry Cell

Carbon (Cathode)
Paste of MnO2 , NH4Cl
e-
Zinc (Anode)
Anode
Zn ? Zn2 2e-
Cathode
2MnO2 2NH4 2e- ? 2MnO(OH) 2NH3
E?cell 1.5 V

• Poor diffusion of products.

• The alkaline battery is similar, but includes a
  salt bridge of KOH and more reactants.

2

• Silver Oxide Battery

Ag2O
KOH
e-
Zn
Anode
Zn ? Zn2 2e-
Cathode
Ag2O 2e- ? 2Ag OH-

• Used for watches, cameras, hearing aids

3

• Lead Storage Battery

e-
fill cap
PbO2
Pb
H2SO4
Anode
Pb SO42- ? PbSO4 2e-
Cathode
PbO2 4H SO42- 2e- ? PbSO4
2H2O
E?cell 2.0 V

• Reactions are reversed by applying an external
  voltage.

• 6 are connected in series 12 V

4

• Fuel Cells

e-
O2 (air)
H2
Porous carbon
KOH
Anode
H2 2OH- ? 2H2O 2e-
Cathode
O2 2H2O 4e- ? 4OH-
Overall
2H2 O2 ? 2H2O

• Produces electricity and water.