Application of germanene monolayers as efficient anchoring material to immobilize lithium polysulfides in Li-S batteries

摘要

The Lithium-sulfur (Li-S) battery chemistries have so far been plagued with difficulties such as the dissolution of intermediate lithium-polysulfides (LPSs) into the electrolyte, the so-called shuttle-effect, causing the capacity loss. Using van der Waals corrected density functional theory approach, we report the outstanding anchoring effect of germanene monolayer (GeM), which can trap the LPSs sturdily without disturbing their integrity. The persistent electrical conductivity of GeM upon adsorption of LPSs demonstrates an effective strategy for the enhanced cyclic performance of Li-S batteries while avoiding the shuttling effect and preventing agglomeration at the battery electrodes. It is found that the LPSs adsorbed to GeM with a moderate assortment between -1.8. to -2.6 eV. In addition to the efficient anchoring performance, the electronic properties of GeM also improve upon the adsorption of LPSs. The diffusion barrier energies of LPSs are very small, thus ensuring their ultrafast diffusion and smooth transition during the charge/discharge process of the Li-S battery.