A super hybrid supercapacitor with high energy density based on the construction of CoMoO4/MoO2 decorated 3D sulfur-doped graphene and porous lotus leaves carbon

Abstract

In this paper, a novel three-dimensional sulfur-doped graphene (3DSG)/cobalt molybdate-molybdenum oxide (CoMoO4-MoO2) framework is prepared by hydrothermal method followed by high-temperature calcination, which effectively combine the advantages of highly conductive sulfur-doped graphene with big specific surface area as well as excellent pseudocapacitive performance of molybdenum cobalt oxide. Comparing with CoMoO4/3DSG, CoMoO4-MoO2/3DSG has the better specific capacity (1022.7 C g−1 at 1 A g−1) and stability performance (retention 95.2% after 5000 cycles). Furthermore, the porous carbon prepared from lotus leaf (PLLC) has uniform pore structure and unique flower surface structure, which is excellent conducive to charge storage. Finally, the asymmetric supercapacitor device is assembled by CoMoO4-MoO2/3DSG as positive electrode and PLLC as negative electrode, which exhibits a specific capacitance of 262.3 F g−1 at a current density of 1 A g−1, provides a maximum energy density of 58.6 Wh kg−1 at a power density of 801.0 W Kg−1, and satisfies the reversibility with a cycling efficiency of 95.0% after 5000 cycles. Particularly, when the two devices are connected in series, the window range of the device can be widened to 3.2 V, and the device still has low impedance and cycle stability (maintain 92.3% after 5000 cycles).