dry cell battery

11

Dry Cell BatteryDry Cell Battery

Anode (-)Anode (-)

Zn ---> ZnZn ---> Zn2+2+ + 2e- + 2e-

Cathode (+)Cathode (+)

2 NH2 NH44++ + 2e- ---> + 2e- --->

2 2 NHNH33 + H + H22

22

Nearly same reactions as in common dry Nearly same reactions as in common dry cell, but under basic conditions.cell, but under basic conditions.

Alkaline BatteryAlkaline Battery

Anode (-): Anode (-): Zn + 2 OHZn + 2 OH-- ---> ZnO + H ---> ZnO + H22O + 2e-O + 2e-Cathode (+): Cathode (+): 2 MnO2 MnO22 + H + H22O + 2e- ---> O + 2e- --->

MnMn22OO33 + 2 OH + 2 OH--

33

Anode:Anode:Zn is reducing agent under basic Zn is reducing agent under basic conditionsconditions

Cathode:Cathode:HgO + HHgO + H22O + 2e- ---> Hg + 2 OHO + 2e- ---> Hg + 2 OH--

Mercury BatteryMercury Battery

44Lead Storage BatteryLead Storage BatteryAnode (-) Anode (-) EEoo = +0.36 V = +0.36 VPb + HSOPb + HSO44

-- ---> PbSO ---> PbSO44 + H + H++ + 2e- + 2e-Cathode (+) Cathode (+) EEoo = +1.68 V = +1.68 VPbOPbO22 + HSO + HSO44

-- + 3 H + 3 H++ + 2e- + 2e- ---> PbSO---> PbSO44 + 2 H + 2 H22OO

55

Ni-Cad BatteryNi-Cad BatteryAnode (-)Anode (-)Cd + 2 OHCd + 2 OH-- ---> Cd(OH) ---> Cd(OH)22 + 2e- + 2e-Cathode (+) Cathode (+) NiO(OH) + HNiO(OH) + H22O + e- ---> Ni(OH)O + e- ---> Ni(OH)22 + OH + OH--

66

HH22 as a Fuel as a Fuel

Cars can use electricity generated by HCars can use electricity generated by H22/O/O22 fuel cells.fuel cells.HH22 carried in tanks or generated from carried in tanks or generated from hydrocarbonshydrocarbons

77

Hydrogen—Air Hydrogen—Air Fuel CellFuel Cell

Figure 20.9Figure 20.9

88

Ballard Power SystemsBallard Power Systemshttp://www.http://www.ballardballard.com/.com/

Car using a HCar using a H22 fuel cell fuel cell

A HA H22-based fuel cell-based fuel cell

99

Hybrid fuel car,Hybrid fuel car,page 847page 847