Electrochemical Hybrid Supercapacitors Based on Activated Carbon and Iron Oxides

Hybrid lithium battery-supercapacitor is developed using nanosized electrode materials – activated carbon and iron oxides (magnetite and hematite) and a non-aqueous electrolyte. The hybrid cell is assembled by an electrode of activated carbon, a composite electrode with activated carbon matrix and addition of 50 wt.% Fe3O4 or Fe2O3. Symmetric supercapacitor cell, composed by two identical electrodes of activated carbon is also assembled and tested for comparison. The supercapacitor cells are subjected to charge/discharge cycling test under galvanostatic conditions at different current loads and continuous cycling. The hybrids supercapacitors developed, especially the magnetite based cell, demonstrate high current efficiency (up to 95%) and specific capacity higher (with 20-50%) than the capacities of the basic symmetric capacitor (about 50 Fg-1 ) as well as stable capacity behaviors at prolong cycling. The results prove the possibility of application of magnetite and hematite as electrochemically active material for hybrid lithium battery–supercapacitor systems.