Abstract
With the expanding application of supercapacitors, the industry puts forward higher demand for the energy density ( E ) of supercapacitors. Normally, increasing voltage is more effective means to improve E . However, it is challenging to construct porous carbons that can withstand ultra-high voltage in organic electrolyte. In this study, 2D highly conductive porous carbon nanosheet (CPCN) with uniform thickness of 20 nm is synthesized by the hydrothermal crosslinking, activation and annealing methods from chitosan biomass. The CPCN exhibits reasonable specific surface area of 2199 m 2 g −1 . The CPCN consists of abundant short-range ordered graphite microcrystals with nitrogen-doping content of 1.61 wt% and high sp 2 carbon (88.7 %), thereby contributing to the electrical conductivity as high as 108 S m −1 . Moreover, the CPCN owns low oxygen content of 4.79 wt%, in which the stable carbonyl and ether bonds dominate. Thus the withstanding voltage of CPCN can be up to 3.2 V in TEABF 4 /PC electrolyte. It delivers good specific capacitance of 114.0 F g −1 at 1 A g −1 with rate performance of 78.1 %. And the E can reach 41.9 Wh kg −1 . Significantly, CPCN can own ultralong lifespan of 84.2 % after 50,000 cycles at 2.5 A g −1 . • 2D highly conductive porous carbon nanosheet is constructed from chitosan. • It has ultrathin thickness and high e -conductivity. • The very-low oxygen content guarantees high tolerance towards ultrahigh voltage. • The voltage can be raised up to 3.2 V in TEABF 4 /PC electrolyte. • High energy density up to 41.9 Wh kg −1 and superior lifespan are achieved.
Published Version
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