Since, the biomass are uniformly charged, the Ag nanoparticles could homogeneously be decorated on the carbon material. The XPS analysis showed the presence of multi-heteroatomdoping in the carbon materials. In detail, the XPS spectrum of OC showed the presence of C, O, P, S, Mg, Si, K, and Ca with the at% of %, respectively. The XPS results of EC confirmed the presence of C, N, O, P, S, Cl, Na, and K with the at% of . Further, the presence of C, N, O, P, S, Na, K, and Ag were evident from the XPS analysis of Ag-EC with the atomic percentage of respectively. The electrochemical performance of the prepared materials was tested using a typical three-electrode configuration, in which 2 M KOH aqueous solution as used as a supporting electrolyte. The OC, EC, and Ag-EC electrodes exhibited the specific capacitances of 119.6, 157.2, and 99.2 F g -1 at the current density of 2 A g -1 , respectively. Further, the fabricated OC, EC, and Ag-EC electrodes could retain the specific capacitances of 101.7%, 105.4%, and 107.4%, after 50000 cycles. In addition, the C/N-CoO@CoO/NiO nanomaterials with core-shell structure was prepared in the present study and applied as positive electrode, which delivered the specific capacitance value of 1258.5 F g -1 at 1 A g -1 current density. The same electrode also showed 76.3% capacitance retention at 20 A g -1 , with the cycling stability of 111.6% after 50000 cycling times. The work also presented the fabrication of solid-state hybrid supercapacitors, in which C/N-CoO@CoO/NiO were used as positive electrodes, while OC, EC, and Ag-EC were negative electrodes. The solid-state hybrid supercapacitors showed the energy densities of W h Kg -1 at about 850.0 W Kg -1 , and possessed the super-long-term cycling stability with the specific capacitance retentions of 145.9, 139.2, and 140% after 50000 cycles, for C/N-CoO@CoO/NiO//OC, C/N-CoO@CoO/NiO//EC, and C/N-CoO@CoO/NiO//Ag-EC electrodes, respectively.