Graphene/Sulfur and Graphene oxide/Sulfur composite cathodes for high performance Li-S batteries: A molecular dynamics study

A Dive and R Gonzalez and S Banerjee, PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2016, VOL. 6A, V06AT08A036 (2017).

Lithium sulfur (Li-S) battery, with theoretical capacity (1675 mAh/g) and energy density comparable to that of gasoline, is a promising technology meeting the demands of next-generation electric vehicles. However, the Li-S battery hasn't been able to reach the theoretically predicted capacity due to several limitations, which include low electrical conductivity of pure sulfur cathode and loss of active material due to dissolution of intermediate polysulfides from the cathode during repetitive charge discharge cycling referred commonly as "polysulfide shuttle". Graphene/Graphene oxide (GO) are being explored as cathodes/cathode supports for Li-S batteries to alleviate these problems. We have employed molecular dynamics simulations to calculate the density distributions of polysulfides (S-8(2-)) in dimethoxy ethane (DME) 2, 4 dioxalane (DOL) electrolyte (1:1 v/v) in the vicinity of different graphene and GO structures, in order to study the impact of hydroxyl functional groups in GO on anchoring polysulfides. Density distribution of polysulfides provides valuable insight on the role of functional groups in successful anchoring of polysulfides onto the GO cathode supports structures.

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