3D flexible O/N Co-doped graphene foams for supercapacitor electrodes with high volumetric and areal capacitances

Abstract 3D flexible O/N co-doped graphene foams (GF) have been designed and fabricated successfully via combining the compression/hot curing strategy with chemical reduction and hydrothermal treatment, in which melamine foams were used not only as the source of N/O functional groups for the introduction of pseudocapacitance but also as the sacrificial template to inhibit the agglomeration of graphene. Also, the mechanism for method of the compressing/hot curing has been investigated systematically. And the resultant GF demonstrates excellent mechanical strength and flexibility. When the compacting GF is used as free-standing electrodes for supercapacitor, it exhibits more excellent ability of charge storage than that of pristine graphene foams. And 10 MPa-GF electrodes delivers high areal capacitance of 375 μF cm −2 at a current density of 1 A g −1 , excellent rate capabilities and superior cycling stability of above 100%. According to the analysis of capacitance contribution for 10 MPa-GF electrode, the pseudocapacitance originated from N/O functional groups is up to ∼65% of the contribution of total capacitance. Moreover, the symmetric supercapacitor comprised of 10 MPa-GF electrodes presents a maximum energy density of 16 Wh kg −1 (8 Wh L −1 ) and a maximum power density of 17 kW kg −1 (8.6 kW L −1 ).