1. Batteries b A galvanic cell, or more commonly, a group of galvanic cells connected in series where the potentials of the individual cells are added to give the total battery potential. b They are a portable source of direct current (D.C.)

2. Series vs. Parallel b If connected in series, the total voltage of the battery is the sum of the voltages of each individual cell. b If connected in parallel, the voltage of the battery will be that of one of the individual cells.

3. Series Vs. Parallel b Each cell is consumed at the same rate simultaneously b Each cell is consumed one at a time, so the life (capacity) of the battery is extended.

4. Dry Cell Batteries Acidic version – 1.5 voltsAcidic version – 1.5 volts –Invented over 100 yrs ago by George LeClanche –Composed of a zinc inner case (anode) and a carbon rod (cathode) in contact with a moist paste of solid MnO 2, solid NH 4 Cl (pH).

5. Dry Cell Battery Cont’d. b Alkaline version- 1.5 volts NH 4 Cl is replaced with KOH or NaOH. Zinc is oxidized, MnO 2 is reduced.NH 4 Cl is replaced with KOH or NaOH. Zinc is oxidized, MnO 2 is reduced. –Tends to last longer as zinc does not corrode as quickly under basic conditions.

6. Dry Cell Battery b Alkaline version Cont’d. In Lithium cells, Li is the anode with most likely MnO 2 as oxidizing agent.In Lithium cells, Li is the anode with most likely MnO 2 as oxidizing agent. –Voltage is @ 3.0 b Silver I oxide cell: Zinc is the anode with Ag 2 O as the oxidizing agent. Has a 1.5 volt potential.Has a 1.5 volt potential.

7. Fuel Cells b A Galvanic cell in which the reactants are continuously supplied from an outside source. b Hydrogen is oxidized, and Oxygen is reduced producing water. b Extremely efficient but very expensive. b Gives a 0.9 volt potential

8. Fuel Cells Cont’d b Used in powering space shuttle b Being developed for replacement of lead/acid battery in vehicles.

9. Storage Batteries (Rechargeables) b The Lead Storage Battery Functions for several years under extreme temperatures and roughest of roads.Functions for several years under extreme temperatures and roughest of roads. Lead serves as the anode and lead coated with lead IV oxide serves as the cathode. Sulfuric Acid serves as the salt bridge or electrolyte.Lead serves as the anode and lead coated with lead IV oxide serves as the cathode. Sulfuric Acid serves as the salt bridge or electrolyte.

10. Storage Batteries Cont’d. b Lead Storage Battery: Each cell provides 2.0 volts w/ 6 cells in series for a total of 12volts.Each cell provides 2.0 volts w/ 6 cells in series for a total of 12volts. Multiple plates of Pb/PbO 2 in each cell are in parallel for long life.Multiple plates of Pb/PbO 2 in each cell are in parallel for long life. It is recharged as the motor runs, the rxn is reversed. (alternator)It is recharged as the motor runs, the rxn is reversed. (alternator)

11. Storage Batteries Cont’d. b Ni/Cd Battery Cd is oxidized, Nickel is reduced from NiOOH to Ni(OH) 2Cd is oxidized, Nickel is reduced from NiOOH to Ni(OH) 2 1.4 voltage1.4 voltage Reaction is reversible when electricity is applied to the battery with the recharger.Reaction is reversible when electricity is applied to the battery with the recharger.