KOH Activated Nitrogen Doped Hard Carbon Nanotubes as High Performance Anode for Lithium Ion Batteries

In situ nitrogen doped hard carbon nanotubes (NHCNT) were fabricated by pyrolyzing tubular nitrogen doped conjugated microporous polymer. KOH activated NHCNT (K-NHCNT) were also prepared to improve their porous structure. XRD, SEM, TEM, EDS, XPS, Raman spectra, N 2 adsorption–desorption, galvanostatic charging–discharge, cyclic voltammetry and EIS were used to characterize the structure and performance of NHCNT and K-NHCNT. XRD and Raman spectra reveal K-NHCNT own a more disorder carbon. SEM indicate that the diameters of K-NHCNT are smaller than that of NHCNT. TEM and EDS further indicate that K-NHCNT are hollow carbon nanotubes with nitrogen uniformly distributed. N 2 adsorption–desorption analysis reveals that K-NHCNT have an ultra high specific surface area of 1787.37 m 2 g −1 , which is much larger than that of NHCNT (531.98 m 2 g −1 ). K-NHCNT delivers a high reversible capacity of 918 mAh g −1 at 0.6 A g −1 . Even after 350 times cycling, the capacity of K-NHCNT cycled after 350 cycles at 0.6 A g −1 is still as high as 591.6 mAh g −1 . Such outstanding electrochemical performance of the K-NHCNT are clearly attributed by its superior characters, which have great advantages over those commercial available carbon nanotubes (200–450 mAh g −1 ) not only for its desired electrochemical performance but also for its easily and scaling-up preparation. Graphical Abstract