The effect of V2O5/C additive on the suppression of polysulfide dissolution in Li-sulfur batteries

Abstract

The effect of adding a V2O5/carbon nano-composite to the cathode of a Li-sulfur battery on suppressing the polysulfide dissolution phenomenon was evaluated by comparing the amount of overcharge at the first discharge–charge processes. V2O5/carbon nano-composite was manufactured by forming V2O5 ⋅H2O xerogel on the carbon black through a simple wet process. This provides a high surface area with plenty of hydrophilic moieties that can capture and store soluble polysulfides on its surface during the discharge–charge reactions, and also partly contributes to suppressing the excessive formation of Li2S which undergoes a large volume change during the cycling. From the electrochemical results, we could observe a significant reduction in the overcharge amount and improved cyclic performance by adding as little as 2 % of the nano-composite. UV–VIS spectra measured after a small addition of the nano-composite to the solution containing Li2S6 polysulfide also confirmed that the V2O5/carbon nano-composite is highly effective in capturing long-chain polysulfides on its surface.