Ultrahigh supercapacitance in cobalt oxide nanorod film grown by oblique angle deposition technique

Nanorod films of cobalt oxide (Co3O4) have been grown by a unique oblique angle deposition (OAD) technique in an e-beam evaporator for supercapacitor electrode applications. This technique offers a non-chemical route to achieve large aspect ratio nanorods. The fabricated electrodes at OAD 80° exhibited a specific capacitance of 2875 F/g. The electrochemically active surface area was 1397 cm−2, estimated from the non-Faradaic capacitive current region. Peak energy and power densities obtained for Co3O4 nanorods were 57.7 Wh/Kg and 9.5 kW/kg, respectively. The Co3O4 nanorod electrode showed a good endurance of 2000 charge-discharge cycles with 62% retention. The OAD approach for fabricating supercapacitor nanostructured electrodes can be exploited for the fabrication of a broad range of metal oxide materials.