Preparation of N/Ni co-doped cellulose-based porous carbon and its supercapacitor performance

A green and effective nitrogen and nickel in-situ doping strategy was designed to prepare cellulose-based N/Ni co-doped porous carbon (PC). The co-hydrothermal pretreatment induced by hydrazine hydrate and nickel acetate effectively modifies the physico-chemical structure of PC and further improves its electrochemical performance. The efficient N-supply and unique heteroatom regulation performance of hydrazine hydrate is related to its strong reducibility. The specific surface area and total pore volume of the synthesized N4NiPC220-3 are 1383.66 m2 g−1 and 0.59 cm3 g−1, while the N and O contents are 1.35 and 10.41%, respectively. At current densities of 0.5 and 20 A g−1, N4NiPC220-3 exhibits a high specific capacitance of 415 F g−1 and a good capacitance retention of 72.22%, respectively. After 10,000 charge/discharge cycles, the retention rate is as high as 96.06%, confirming its excellent cycling stability. The two-electrode system test results further show that the energy density of N4NiPC220-3 is as high as 35.6 W h kg−1 at a power density of 500.1 W kg−1, while a high retention rate of 87.87% is still obtained after 10,000 cycles. This green and efficient synthesis method based on in-situ co-doping of hydrazine hydrate and nickel acetate is a promising alternative strategy for producing carbon-based supercapacitors.