▎ 摘　　要

Battery-supercapacitor hybrid (BSH) devices with aqueous electrolytes receive extensive attention due to their high potential. In this study, porous carbon coated Fe3C nanopartides (C/Fe3C) are loaded onto reduced graphene oxide (rGO) nanosheets, forming rGO@C/Fe3C composite structure. The rGO@C/Fe3C composite is prepared by in-situ carbonization of rGO/Fe-MOFs. First-principles calculation proves that the high conductivity of the Fe3C mainly comes from d electrons of Fe and therefore can benefit the rate capability. The optimized electrode structure of rGO@C/Fe3C displays high capacity of 95.3 mAh g(-1) at 1 A g(-1), enhanced rate performance (retaining 66.5% at 20 A g(-1)) and outstanding cycling stability (retaining 81.5% after 5000 cycles). Furthermore, a BSH device with Na0.5MnO2 cathode and rGO@C/Fe3C anode structure shows an ultrahigh output voltage of 2.4 V in 1 M Na2SO4 electrolyte, while its output voltage in 6 M KOH electrolyte is only 1.4 V. The observed energy densities of the device in two electrolytes are 46.2 Wh kg(-1) at 1.2 kW kg(-1) and 28.3 Wh kg(-1) at 0.7 kW kg(-1), respectively. Therefore, the successful construction of the BSH device based on Fe3C/rGO provides an attractive strategy for the selection of anode materials.