Corn stalk-derived activated carbon with a stacking sheet-like structure as sulfur cathode supporter for lithium/sulfur batteries

A novel stacking sheet-like carbon (SSC) has been synthesized by carbonizing the corn stalks and composited with sulfur to prepare a cathode for lithium/sulfur batteries. Scanning electronic microscopy observations showed the formation of irregularly interlaced nanosheet-like structure consisting SSC with uniform sulfur coating on its surface. The SSC nanoflakes in the composite act as nanocurrent collectors, favoring the charge carrier ion transport and electrolyte diffusion. The interlaced SSC nanoflakes irregularly stack together and form a three-dimensional network, which is beneficial for both trapping soluble polysulfide intermediates and rendering the electrical conductivity of the composite electrode. A lithium cell employing this sulfur/stacking sheet-like carbon (S/SSC) composite cathode delivered an initial discharge capacity of 965 mAh g−1 at 0.2 C and retained a capacity of 743 mAh g−1 over 100 charge-discharge cycles. Even at 3.2 C rate, the lithium cell with the S/SSC composite cathode demonstrated an excellent rate capability, delivering a highly reversible discharge capacity of 418 mAh g−1.