Flexible N-doped active carbon/bacterial cellulose paper for supercapacitor electrode with high areal performance

A flexible N-doped activated shaddock peel carbon (N-ASPC)/graphene (GN)/bacterial cellulose (BC) hybrid paper electrode with remarkable mechanical properties and large mass loading (8 mg cm⁻²) is fabricated. This flexible electrode integrates extraordinary special capacitance N-ASPC from resource-rich fruit waste (shaddock peel), highly conductive GN and ultrafine three-dimensional (3D) fibrous network structure BC, which exhibits remarkable areal capacitance of 2004 mF cm⁻² (250.5 F g⁻¹), excellent rate performance with 82.3% retention from 2 to 40 mA cm⁻², good cyclic stability with 97% retention over 10,000 cycles, ultrahigh tensile strength (32 MPa) and good conductivity (1550 S m⁻¹). The symmetric supercapacitor based on two identical N-ASPC/GN/BC film electrodes with an operation voltage of 1.4 V in Na₂SO₄ electrolyte can deliver a maximum energy density of 0.158 mW h cm⁻² and a maximum power density of 28 mW cm⁻². Therefore, the binder-free N-ASPC/GN/BC electrodes hold great promise for flexible energy-storage devices.