CHE 2C Batteries

Lead (Acid) Storage

• Anode: Pb (both electrodes dip into H2SO4

• Cathode: Pb/PbO

• anode reaction: Pb + HSO4- —> PbSO4 + H+ + 2e-

• cathode reaction: PbO2 + HSO4- + 3H+ + 2e- —> PbSO4 + 2H2O

• cell reaction: Pb(s) + PbO2(s) + 2H+(aq) + 2HSO4-(aq) —> 2PbSO4(s) + 2H2O(l)

• cell potential: 6cells x 2V = 12V

• charged by alternator, recharged by jump start

• ex) car battery

Dry Cell (Leclanche) Acid Version

• anode: Zn inner case

• cathode: NH4Cl / C in MnO2

• anode reaction: Zn —> Zn2+ + 2e-

• cathode reaction: 2NH4+ + 2MnO2 + 2e- —> Mn2O3 + 2NH3 + H2O

• Cell potential: 1.5V

• corrosive

Dry Cell (Leclanche) Alkaline Version

• anode: Zn + 2OH- —> ZnO + H2O + 2e-

• cathode: 2MnO2 + H2O + 2e- —> Mn2O3 + 2OH-

• zinc corrodes less rapidly under basic conditions, so these batteries hold charge for a long time, have a longer shelf life and longer working time

• better version

Silver Cell

• anode: Zn

• cathode: Ag2O / basic medium

Mercury Cell

• anode: Zn

• cathode: HgO / basic medium

• ex) calculators

Nickel-Cadmium Battery

• anode: Cd / OH-

• cathode: NiO2

• anode reaction: Cd + 2OH- —> Cd(OH)2 + 2e-

• cathode reaction: NiO2 + 2H2O + 2e- —> Ni(OH)2 + 2OH-

• rechargeable

Lithium-Ion Batteries

• anode: Li2C6

• cathode: Li2CoO2

• lithium-ion batteries are used in a wide variety of applications including cell phones, laptop computers, power tools, and even electric drive systems in automobiles and motorcycles

Fuel Cells

• anode: H2 / OH-

• cathode: O2

• anode reaction: 2H2 + 4OH- —> 4H2O + 4e-

• cathode reaction: 4e- + O2 + 2H2O —> 4OH-

• the cell burns cleanly because water is the only by-product

• highly efficient (80-90%) than mechanical electrical generators (40-50%)

• but every expensive, a bus using fuel cell costs 1.4 million

Wet Batteries

has sulfuric acid (only lead acid storage)

Dry Batteries

has no solution