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Chitosan-based carbon materials have attracted great attention in electrochemical energy storage. Introducing iron metal or iron compounds into carbon materials favors to boost their electrochemical performance. Herein, chitosan-based graphitic carbon@Fe3C composites (CSGC@Fe3C) have been prepared as anode materials for lithium ion battery by a simple pyrolysis method. By manipulating the temperature higher than 700 °C, pure Fe3C encapsulated in chitosan-based graphitic carbon with different mass ratio from 30 to 53.8 wt% can be achieved. The resulting CSGC@Fe3C composites retain porous carbon sheet structure embedded with a large amount of Fe3C nanoparticles in size from 20 to 300 nm. The electrochemical measurements demonstrate CSGC@Fe3C with 53.8 wt% Fe3C as anode material for lithium ion battery can provide a highest reversible capacity of 423 mAh g−1 at 0.1 A g−1 over 100 charge/discharge cycles and stable cycling capacity of 195 mAh g−1 at a high current density of 2 A g−1 during 200 cycles. The catalysis of Fe3C on the reversible formation and decomposition of solid electrolyte interphase (SEI) has been corroborated and results in the improvement of surface capacitive contribution. This work provides a basic insight into metal carbides constructing biomass-based carbon anode materials to realize high-performance electrochemical energy storage device. [ABSTRACT FROM AUTHOR]

Conversion of biomass waste into nitrogen‐doped porous carbon has been considered as a promising approach to achieve energy storage materials. Nitrogen‐doped activated carbon materials have been successfully prepared by molten salt pyrolysis (MSP) using melamine modified‐denim fabric waste as precursor. The molten salt medium provides liquid condition to carbonize and activate the denim fabric waste. Melamine produces a large amount of nitrogen element for doping the carbon materials. The obtained nitrogen‐doped denim fabric‐based carbon materials (NDFC‐MSP) are composed of small fibrous fragment and thin sheet, and exhibit a high specific surface area (1975.2 m2⋅g−1) and high pore volume (1.087 cm3⋅g−1). Moreover, NDFC‐MSP sample with a high nitrogen content of 6.93 wt.% possesses a maximum specific capacitance of 345.8 F⋅g−1 at 0.25 A⋅g−1 in 6 M KOH electrolyte. It also displays a high specific capacitance of 230 F⋅g−1 at 10 A⋅g−1. The cycle stability shows 95.5% retention after 5000 charge‐discharge cycles at 1 A⋅g−1. In addition, the fabricated symmetric NDFC‐MSP supercapacitor with a wide voltage range of 1.8 V generates a maximum energy density of 17.0 Wh⋅kg−1 at power density of 225 W kg−1 in 1 M Na2SO4 aqueous electrolyte. [ABSTRACT FROM AUTHOR]