Enriched energy storage capability and bi-functional ability of boron-doped graphene as efficient electrode for supercapacitors and lithium sulfur batteries

摘要

This work depicts the preparation of boron-doped graphene (BG) and its application as bi-functional electrode material for both the supercapacitors and lithium-sulfur (Li-S) battery. Structural, morphological, and elemental analyses of the prepared material were acquired via X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, Scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. BG worked well in supercapacitors as a capacitive electrode, featuring a high specific capacitance of 239 F g~(-1) at a current rate of 1 A g~(-1) and high capacity retention of 85% over 10,000 charge/discharge cycles with average coulombic efficiency of 99.5%. In addition, the sulfur/boron-doped graphene (SBG) binary composite was prepared via melt diffusion method and used as the positive electrode material in Li-S batteries. BG is effective polysulfide adsorbent and its sheet-like structure accommodates more content of sulfur, which restricts the shuttle effect and volume changes of active material during cycling. The SBG composite shows an initial discharge capacity of 1355 mAh g~(-1) and it retains the discharge capacity of 636 mAh g~(-1) over the 50 cycles. The present work demonstrates that BG is an efficient electrode material for energy storage applications.