Nitrogen-doped activated carbon for a high energy hybrid supercapacitor

Nitrogen-doped activated carbons (NACs) were prepared through a one-step process. The obtained NACs show high surface areas of up to 2900 m super(2) g super(-1) with a moderate N content of up to 4 wt%. Electrochemical evaluation of the NACs shows a high specific capacity of 129 mA h g super(-1) (185 F g super(-1)) in an organic electrolyte at a current density of 0.4 A g super(-1), as well as excellent rate capability and cycling stability. The hybrid-type supercapacitor assembled using the NACs and a Si/C electrode exhibits a high material level energy density of 230 W h kg super(-1) at 1747 W kg super(-1). The hybrid device achieved 76.3% capacity retention after 8000 cycles tested at 1.6 A g super(-1).