Research scientists are developing a rechargeable lithium–carbon dioxide, Li–CO2, battery - VCE - SSCE Chemistry - Question 4 - 2020 - Paper 1

To formulate the overall recharge reaction, we first need to combine the two half-cell reactions provided:

1. From the two half-cell reactions, we can write:

   • Reduction half-reaction:
     $4 ext{Li}^+ + 3 ext{CO}_2 + 4 ext{e}^- → 2 ext{Li}_2 ext{CO}_3 + ext{C}$
   • Oxidation half-reaction:
     $ext{Li} → ext{Li}^+ + ext{e}^-$

2. To write the overall reaction, we need to balance the electrons. Since there are 4 electrons in the reduction reaction, we need to multiply the oxidation reaction by 4:

   • Overall oxidation reaction:
     $4 ext{Li} → 4 ext{Li}^+ + 4 ext{e}^-$

3. Now, combining the modified oxidation half-reaction with the reduction half-reaction, we get:

   $4 ext{Li} + 3 ext{CO}_2 → 2 ext{Li}_2 ext{CO}_3 + ext{C}$

This equation represents the overall recharge reaction for the Li–CO2 cell.