Lithium batteries are a result of some bizarre chemistries, which are not necessarily taught in freshman chemistry. It may seem undaunting for a new chemist, but with a good basic knowledge of atomic and molecular theory you can start to understand things quickly. Consider the phenomena of Li intercalation of graphite at the anode of a Lithium Ion battery, something you should have run across in your review. Intercalation of lithium metal in between the layers of graphite forms a thermodynamically stable compound whose formula is LiC6. At the cathode of a lithium ion battery is another bizarre chemical, typically lithium cobalt oxide (LiCoO2). The two half cell reactions can be expressed as follows:
Li+1 + e- + C6 à LiC6 Eo = -2.84 V
Li+1 + e- + CoO2 à LiCoO2 Eo = +0.25 V
A. Which of the two reactions will undergo reduction and which one will undergo oxidation when the battery discharges (spontaneous reaction)?
B. What is the theoretical voltage that can be produced by this cell at standard conditions? Show your work.
C. Use the above information to write the complete spontaneous redox reaction that combines the half cell reactions.
D. Calculate the standard Gibb's free energy, DGo for this reaction. Calculate the equilibrium constant for this reaction at 25oC.
E. Explain how your typical LiCO2/LiC6 cell could possibly have a higher voltage (3.6 V) than the voltage you calculated above for a cell at standard conditions?