Nitrogen-doped porous carbons derived from a natural polysaccharide for multiple energy storage devices

Designing advanced carbon electrodes is considered as one of the most promising directions for energy storage. Herein, we report a facile approach to produce porous carbon nanomaterials. The carbon nanomaterials were prepared via KOH activation using natural polysaccharide-sodium alginate as the precursor with the subsequent introduction of additional nitrogen heteroatoms achieved by further reaction with urea. The optimal electrodes with a high specific surface area (up to 3313 m(2) g(-1)), interconnected porosity, and rich nitrogen (similar to 7.2 wt%) and oxygen (similar to 7.4 wt%) doping can achieve an excellent electrochemical performance in supercapacitors and lithium ion batteries. When these materials are employed as supercapacitor electrodes, they achieved an outstanding specific capacitance of 267 F g(-1) at 1 A g(-1) and an extremely high rate performance with 76.8% capacitance retention ratio in an alkaline electrolyte. In addition, a high capacitance of 197 F g(-1) at 0.5 A g(-1) with a high capacitance retention ratio of 52.9% at 100 A g(-1) can be achieved in an ionic liquid electrolyte. When tested as lithium ion battery anodes, an extraordinarily high specific capacity of 1455 mA h g(-1) and a stable energy storage performance up to 500 cycles were observed. The present study highlights that high-performance carbon electrodes can be produced by using sustainable precursor and can be used in multiple energy storage systems.