Template-free fabrication of hollow N-doped carbon sphere (h-NCS) to synthesize h-NCS@PANI positive material for MoO3//h-NCS@PANI asymmetric supercapacitor

Abstract Asymmetric supercapacitors (ASCs) based on pseudocapacitor electrode materials are vital to improve the electrochemical properties of devices in aqueous electrolytes. This study fabricates hollow N-doped carbon sphere (h-NCS) to produce h-NCS@PANI nanocomposite as positive electrode and α-MoO 3 as negative electrode to assemble ASC device. In particular, a facile template-free synthesis method, catalyzed by Cu 2+ , is used to prepare hollow PANI nanosphere precursor to build h-NCS. The mechanism of the precursor formation is illustrated in detail. After polymerization of PANI on the surface of h-NCS, the capacitance increases to 327 F g −1 at 1 A g −1 . Furthermore, a hydrothermal reaction is carried out to produce α-MoO 3 negative electrode material. The maximum specific capacitance of 720 F g −1 is achieved at 1 A g −1 . The obtained h-NCS@PANI and α-MoO 3 are utilized to construct an ASC device. The electrochemical properties of this device are investigated comprehensively. The maximum energy density of 34.1 W h kg −1 and power density of 9350.6 W kg −1 are observed, which provide an insight into the development of ASCs.