Effect of Activated Carbon on Re-Conversion Reaction of Cu/LiCl/C Electrode with LiPF6/Methyl Difluoroacetate Electrolyte

Transition-metal chlorides are known to suffer from dissolution in organic solvents. However, our previous investigation revealed that in the Li/CuCl2 battery, the dissolution of CuCl2 cathode materials could be suppressed by using LiPF6/methyl difluoroacetate (MFA; CHF2COOCH3) electrolyte. And, the Cu/LiCl electrode could both charge and discharge in LiPF6/methyl difluoroacetate (MFA) electrolyte as the re-conversion reaction cathode of Li/CuCl2 battery. However, the capacity is only half the theoretical value of 399 mAh g–1. This is because cuprous is hardly oxidized to cupric during charging due to copper disproportionation reaction.

In this study, activated carbon was added to the Cu/LiCl electrode in order to promote the production of CuCl2, and to improve the capacity. The physical properties of the activated carbon were found to have significant effects: activated carbon with a large specific surface area and micropore volume enabled CuCl2 deposition, and improved the capacity of the Cu/LiCl/C electrode to approximately 300 mAh g–1.