Lithium-sulfur batteries (LSBs) are a promising alternative to lithium-ion batteries because
sulfur is highly abundant and exhibits a high theoretical capacity (1675 mAh g-1). However, polysulfide
shuttle and other challenges have made it difficult for LSBs to be commercialised. Here, a sulfur/carbon
(S/C) composite was synthesised and cathodes were fabricated via scalable melt diffusion and slurry
casting methods. Carbon nanoparticles (C65) were used as both sulfur host and electrical additive.
Various carbon ratios between the melt-diffusion step and cathode slurry formulation step were
investigated. An increased amount of C65 in melt-diffusion led to increased structural heterogeneity in
the cathodes, more prominent cracks, and a lower mechanical strength. The best performance was
exhibited by a cathode where 10.5 wt% C65 (TC10.5) was melt-diffused and 24.5 wt% C65 was
externally added to the slurry. An initial discharge capacity of ~1500 mAh g-1 at 0.05 C and 800 mAh g-1
at 0.1 C was obtained with a capacity retention of ~50% after 100 cycles. The improved electrochemical
performance is rationalised as an increased number of C-S bonds in the composite material, optimum
surface area, pore size and pore volume, and more homogeneous cathode microstructure in the TC10.5
cathode.