Tailoring commercially available raw materials for lithium-sulfur batteries with superior performance and enhanced shelf life

Physical activation with CO2 is used to modify the micro-, meso-, and macropore system of commercial, highly branched carbon black (CB) particles. Due to the increased total porosity and high surface area of 1747 m2 g−1 the completeness of sulfur infiltration in intra-particle pores of CB is promoted. This is found to not only minimize sulfur agglomeration on the particle surface but also reduce self-discharge, that is, polysulfide leakage. Wrapping the CB/sulfur composite with a poly(ethylene oxide)/poly(vinylpyrrolidone) film further triggers a synergy allowing for faster sulfur conversion with increased reversibility. Thus, an initial capacity of 1238 mAh g−1S at C/10 and a stable capacity of 1015 mAh g−1S after 50 cycles were obtained, combined with a superior rate capability up to 2 C (≈7.5 mA cm−2) and extremely slow self-discharge over 100 days (open-circuit voltage>2.30 V).