Electrochemical behaviors of graphene–ZnO and graphene–SnO2 composite films for supercapacitors

Graphene, graphene–ZnO and graphene–SnO2 films were successfully synthesized and used as electrode materials for electrochemical supercapacitors, respectively. The screen-printing approach was employed to fabricate graphene film on graphite substrate while the ZnO and SnO2 were deposited on graphene films by ultrasonic spray pyrolysis. The electrochemical performances of these electrodes were comparatively analyzed through electrochemical impedance spectrometry, cyclic voltammetry and chronopotentiometry tests. The results showed that the incorporation of ZnO or SnO2 improved the capacitive performance of graphene electrode. Graphene–ZnO composite electrode exhibited higher capacitance value (61.7 F/g) and maximum power density (4.8 kW/kg) as compared with graphene–SnO2 and pure graphene electrodes.