Electrochemical capacitance performance of polyaniline/tin oxide nanorod array for supercapacitor

A binary nanocomposite of polyaniline/tin oxide nanorod array (PANI/SnO2 NRA) was developed as an electrode material for energy storage. SnO2 NRA supported on the substrate of carbon fibers was prepared by the seed-assisted hydrothermal synthesis method. PANI/SnO2 NRA was then obtained by depositing PANI nanowires onto SnO2 NRA through an electro-polymerization process. SnO2 NRA presents quadrangular prism shape with a side length of 5060 nm. PANI nanolayer is loaded into the interspace of the neighboring SnO2 nanorods to form the core-shell-structured PANI/SnO2 NRA. Additional PANI nanowires with a diameter of 100150 nm are formed on the top surface of PANI/SnO2 NRA. Well-designed PANI/SnO2 NRA benefited a directional electron transfer along with highly ordered SnO2 nanorods during an electrochemical reaction process. The interface layer between SnO2 nanorods and PANI could act as the buffer space to restrain the volumetric change of PANI during the cycling charge-discharge process. Considering electroactive PANI, PANI/SnO2 NRA exhibited higher specific capacitance of 367.5 F g(-1) at 0.5 A g(-1) than that of 232.4 F g(-1) for bare PANI film. The capacitance retention ratio was enhanced from 60.4% for PANI film to 88.3% for PANI/SnO2 NRA after 2000 cycles even at a high current density of 5 A g(-1). All-solid-state PANI/SnO2 supercapacitor was also constructed using symmetric PANI/SnO2 NRA electrodes and sulfuric acid-polyvinyl alcohol gel electrode, presenting the specific capacitance of 44.9 F g(-1), the energy density of 20.2 Wh Kg(-1), and the output voltage of 1.8 V at 0.2 A g(-1) when both PANI and SnO2 were considered as electroactive materials. PANI/SnO2 NRA with high capacitance performance presents the promising supercapacitor applications for the electrochemical energy storage.