Effect of conductive carbon on capacity of iron phthalocyanine cathodes in primary lithium batteries

The effect of conductive carbon type and loading was examined for the iron phthalocyanine (FePc) cathode in primary lithium (Li) batteries. The use of nano graphene platelets (NGPs) as a conductive carbon was shown to increase the discharge capacity by a factor of at least 2.5 compared to typical carbon blacks and vapor grown carbon fibers. Discharge capacities of up to 2050 mAh g−1 FePc, corresponding to the insertion of 43 Li+, were obtained for FePc based cathodes with 25% NGPs. This is the highest cathode capacity reported in literature to our knowledge. Cathodes with 10% NGP still demonstrated reasonable capacities. Electrolyte solutions based on propylene carbonate demonstrated higher discharge voltages than those with the 1.2 M lithium tetrafluoroborate in γ-butyrolactone and 1,2-dimethoxyethane (1:1 by volume).

► Nano graphene platelets (NGPs) are shown to improve iron phthalocyanine (FePc) discharge capacity. ► Capacities of up to 2050 mAh g−1 FePc corresponding to the insertion of 43 Li+ are demonstrated. ► NGP loadings of 10 mass % demonstrate a capacity of 860 mAh g−1 FePc at a rate of 1 mA cm−2. ► FePc is shown to be a potential cathode material for next generation primary Li batteries.