Electrochemistry - Different types of Batteries

Electrochemistry - Different types of Batteries

Prepared by N. R. Mahalingam

Property	Leclanche Cell		Mercury Button cell		Lead Storage Battery
Anode	Zinc container		Zinc amalgamated with mercury		Spongy Lead
Cathode	Graphite rod in contact with MnO2		HgO mixed with graphite		Lead Plate bearing PbO2
Electrolyte	NH4Cl and ZnCl2 in water		Paste of KOH and ZnO		38% by mass of H2SO4 with density 1.2g/mL
Emf of the  cell	1.5 V		1.35V		2V (usually sx cells are combined in series to produce 12 volt)
Oxidation at Anode	Zn (s) → Zn2+ (aq)+2e-		Zn(s) + 2OH- (aq) → ZnO(s) + H2O(l)+ 2e-		Pb(s) →  Pb2+(aq)+2e- Pb2+(aq) + SO42- (aq) → PbSO4 (s)
Reduction at Cathode	2 NH4+(aq) + 2e- →  2NH3(aq) + H2(g) H2(g) + 2MnO2(s) → Mn2O3(s) + H2O (l)		HgO(s) + H2O (l) + 2e- → Hg(l) + 2OH- (aq)		PbO2(s) + 4H+(aq) + 2e- → Pb2+ (aq) + 2H2O Pb2+ (aq) + SO42- (aq) → PbSO4(s)
Overall reaction	Zn (s) + 2NH4+ (aq) + 2 MnO2(s) → Zn2+ (aq) + Mn2O3 (s) + H2O(l)+2NH3		Zn(s) + HgO(s) → ZnO(s)+ Hg(l)		Pb(s) + PbO2(s) + 4H+(aq) + 2SO42-(aq) → 2 PbSO4(s) + 2H2O(l)
Uses			It has a higher capacity and longer life. Used in pacemakers, electronic watches, cameras etc.,		Used in automobiles. trains, inverters etc.,
Type	Battery  (Use and Throw)		Battery  (Use and Throw)		Secondary Battery
Property		Lithium Ion Battery		Hydrogen Oxygen Fuel cell
Anode		Porous Graphite		Porous graphite electrode containing Ni and NiO serves as inert electrodes
Cathode		Transition metal oxide such as CoO2
Electrolyte		Lithium salt in an organic solvent		Aqueous KOH maintained at 200º C and 20 - 40 atm
Emf of the  cell
Oxidation at Anode		Li (s) → Li+ (aq) + e-		2H2(g) + 4OH- (aq) → 4 H2O(l) + 4e-
Reduction at Cathode		Li+ + CoO2 (s) + e- → LiCoO2 (s)		O2 (g) + 2H2O(l) + 4e- →  4OH- (aq)
Overall reaction		Li (s) + CoO2 (s) → LiCoO2 (s)		2H2(g) + O2 (g) → 2 H2O(l)
Uses		Used in Cellular phones, Laptops, Computers, Digital cameras etc.,		They are a clean, reliable source of power to cities, towns and buildings. These fuel cells are also used for back-up and remote power applications including remote weather stations and rural locations.
Type		Secondary  Battery		Secondary Battery

N. R. Mahalingam, Lecturer, District Institute of Education and Training Palayampatti