Defect-rich N-doped porous carbon derived from alginate by HNO3 etching combined with a hard template method for high-performance supercapacitors

Abstract

N-doped porous carbons have recently drawn increasing attention for energy storage devices due to large surface area, various N configurations, and environment friendliness. In this work, we have reported a defect-rich N-doped porous carbon (DNPC) derived from alginate via the combined processes of crosslinking sodium alginate (SA) by CaCO3 hard template, a high-temperature carbonization, as well as HNO3 etching for high-performance supercapacitors (SCs). The specific surface area and pore volume of the optimized DNPC sample are 1117 m2 g−1 and 1.01 cm3 g−1, respectively. The effects of preparation parameters on structural features and electrochemical properties, including the mass ratios of CaCO3 to SA, heating temperatures, and dosages of HNO3, are extensively investigated. Thanks to the advantages of developed porous structure, controllable N configurations, and large specific surface area, the DNPC1 sample displays superior specific capacitance (296 F g−1) and outstanding capacitance retention of 91% after 10000 cycles at 5 A g−1. Additionally, a symmetrical SC with DNPC1 delivers energy densities of 12.9 and 18.9 W h kg−1 in KOH and Na2SO4 electrolytes, respectively. This study presents a facile way to fabricate the N-doped porous carbons with controllable N configurations for energy storage devices.