User interface language: English | Español

Date May 2009 Marks available 2 Reference code 09M.3.sl.TZ2.C3
Level SL Paper 3 Time zone TZ2
Command term Describe Question number C3 Adapted from N/A

Question

The high activity of lithium metal leads to the formation of an oxide layer on the metal which decreases the contact with the electrolyte in a battery.

Describe how this is overcome in the lithium-ion battery.

[2]
a.

Describe the migration of ions taking place at the two electrodes in the lithium-ion battery when it produces electricity.

Anode (–):

Cathode (+):

[2]
b.

Discuss one similarity and one difference between fuel cells and rechargeable batteries.

Similarity:

Difference:

[2]
c.

Markscheme

contains no lithium/metal / uses lithium salt in an organic solvent (as electrolyte);

involves movement of lithium ions (between electrodes);

a.

Anode (–):

\({\text{Li}}{{\text{C}}_{\text{6}}} \to {\text{L}}{{\text{i}}^ + } + {\text{6C}} + {{\text{e}}^ - }/{\text{L}}{{\text{i}}^ + }\) ions dissociate from anode (and migrate to cathode);

Cathode (+):

\({\text{L}}{{\text{i}}^ + } + {{\text{e}}^ - } + {\text{Mn}}{{\text{O}}_{\text{2}}} \to {\text{LiMn}}{{\text{O}}_{\text{2}}}\) / \({\text{L}}{{\text{i}}^ + } + {{\text{e}}^ - } + {\text{Co}}{{\text{O}}_{\text{2}}} \to {\text{LiCo}}{{\text{O}}_{\text{2}}}\) / \({\text{L}}{{\text{i}}^ + } + {{\text{e}}^ - } + {\text{FeP}}{{\text{O}}_{\text{4}}} \to {\text{LiFeP}}{{\text{O}}_{\text{4}}}\) / \({\text{L}}{{\text{i}}^ + } + {{\text{e}}^ - } + {\text{Ni}}{{\text{O}}_{\text{2}}} \to {\text{LiNi}}{{\text{O}}_{\text{2}}}\) / \({\text{L}}{{\text{i}}^ + }\) ions are inserted into metal oxide/phosphate (structure);

Award [1] if electrodes are reversed.

b.

Similarity:

both convert chemical energy directly into electrical energy / both use spontaneous redox reactions (to produce energy) / both are electrochemical cells/voltaic cells/galvanic cells;

Difference:

fuel cells are energy conversion devices and rechargeable batteries are energy storage devices / fuel cells require constant supply of reactants and batteries have stored chemical energy/provide power until stored chemicals are used up / batteries can be recharged and fuel cells do not need recharging (have a continuous supply of fuel) / fuel cells are more expensive than rechargeable batteries / the reactions in a rechargeable battery are reversible and in a fuel cell are not;

c.

Examiners report

Only the better candidates described how the lithium-ion battery overcomes the reactivity of lithium.

a.

The description of the migration of ions was poor.

b.

The similarity and difference of fuel cells and rechargeable cells had better resposes.

c.

Syllabus sections

Options » C: Energy » C.6 Electrochemistry, rechargeable batteries and fuel cells (HL only)
Show 39 related questions

View options