Effects of Porous Carbon Cathode Additives on the Electrochemical Performance of Li–S Cells

In this paper, the effects of porous carbon additives, which included microporous, mesoporous and macroporous carbon, on the electrochemical properties of a sulfur cathode were examined. The type of carbon additive significantly affected the initial capacity reduction, though it did not affect the cycling stability of the sulfur cathodes. The cathodes that incorporated mesoporous and macroporous carbon additives delivered much higher initial capacities of ∼970 and ∼900 mAh/g, respectively, compared with those (∼715 mAh/g) with graphite and microporous carbon additives. The EDS results showed that these features are strongly related to the absorption characteristics of the carbon additives. Importantly, it was found that the macroporous carbons with a pore size of ∼65 nm effectively confined dissolved polysulfides. Interestingly, the sulfur cathodes with microporous carbon additives exhibited extremely similar electrochemical behavior to those with nonporous graphite, which suggests that activated carbon particles do not serve as polysulfide reservoirs during discharge.